$147+ Cheap flights from Seattle (SEA) to Illinois
This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 7/4. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Jul 20 — Jul 271
Round-trip
1 adult, Economy
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Find cheap flights from Seattle to Illinois with Cheapflights
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Cheapest flights from Seattle to IllinoisExplore the most affordable flight options available from Seattle to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 20, 2026.
Explore the most affordable flight options available from Seattle to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 20, 2026.
This American Airlines deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/131:17 am
SEA
- PIA
1 stop5h 45m
American Airlines
Wed 10/219:59 am
PIA
- SEA
1 stop7h 21m
American Airlines
Deal found 6/18![American Airlines logo]()
$271
This American Airlines deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/122:07 pm
SEA
- PIA
1 stop7h 12m
American Airlines
Sat 8/226:47 pm
PIA
- SEA
1 stop7h 26m
American Airlines
Deal found 6/16![American Airlines logo]()
$310
This Kiwi.com deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/128:13 pm
SEA
- MLI
1 stop13h 28m
Multiple Airlines
Sun 8/231:06 pm
MLI
- SEA
1 stop23h 33m
Multiple Airlines
Deal found 6/18![Multiple Airlines logo]()
$332
This Delta deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/1511:59 pm
SEA
- BMI
1 stop9h 24m
Delta
Tue 9/294:23 pm
BMI
- SEA
1 stop9h 36m
Delta
Deal found 6/18![Delta logo]()
$343
This American Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/135:00 am
SEA
- BMI
1 stop9h 19m
American Airlines
Sat 8/155:40 pm
BMI
- SEA
1 stop8h 33m
American Airlines
Deal found 6/19![American Airlines logo]()
$346
This Delta deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/1511:59 pm
SEA
- BMI
1 stop9h 24m
Delta
Wed 9/3012:08 pm
BMI
- SEA
2 stops11h 54m
Delta
Deal found 6/18![Delta logo]()
$348
This Delta deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/156:00 am
SEA
- MLI
1 stop8h 22m
Delta
Wed 9/235:10 pm
MLI
- SEA
1 stop8h 49m
Delta
Deal found 6/18![Delta logo]()
$349
This American Airlines deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/83:28 pm
SEA
- PIA
1 stop6h 54m
American Airlines
Tue 7/146:58 pm
PIA
- SEA
1 stop7h 54m
American Airlines
Deal found 6/15![American Airlines logo]()
$349
This Delta deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/1411:05 pm
SEA
- BMI
2 stops10h 18m
Delta
Tue 9/294:23 pm
BMI
- SEA
1 stop9h 36m
Delta
Deal found 6/18![Delta logo]()
$351
This Kiwi.com deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/155:48 pm
SEA
- ORD
Nonstop4h 11m
Multiple Airlines
Thu 8/208:11 pm
ORD
- SEA
1 stop16h 28m
Multiple Airlines
Deal found 6/19![Multiple Airlines logo]()
$352
This Orbitz deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/2512:17 am
SEA
- ORD
Nonstop4h 03m
Multiple Airlines
Mon 6/299:48 pm
ORD
- SEA
1 stop14h 00m
Multiple Airlines
Deal found 6/19![Multiple Airlines logo]()
$353
This Southwest deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/66:10 pm
SEA
- MDW
2 stops9h 35m
Southwest
Tue 8/1110:10 am
MDW
- SEA
2 stops9h 20m
Southwest
Deal found 6/18![Southwest logo]()
$353
Best flights from Seattle to IllinoisDiscover carefully curated flight deals from Seattle to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 20, 2026.
Discover carefully curated flight deals from Seattle to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 20, 2026.
This Delta deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/76:00 am
SEA
- MLI
1 stop8h 22m
Delta
Mon 9/145:10 pm
MLI
- SEA
1 stop8h 49m
Delta
Deal found 6/19![Delta logo]()
$349
This Alaska Airlines deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/155:48 pm
SEA
- ORD
Nonstop4h 11m
Alaska Airlines
Sat 7/258:20 pm
ORD
- SEA
Nonstop4h 44m
Alaska Airlines
Deal found 6/18![Alaska Airlines logo]()
$355
This United Airlines deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/145:13 pm
SEA
- ORD
Nonstop4h 04m
United Airlines
Thu 9/178:01 pm
ORD
- SEA
Nonstop4h 44m
United Airlines
Deal found 6/16![United Airlines logo]()
$355
This Southwest deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/311:05 pm
SEA
- MDW
Nonstop3h 55m
Southwest
Tue 7/76:40 pm
MDW
- SEA
1 stop7h 55m
Southwest
Deal found 6/16![Southwest logo]()
$365
This Kiwi.com deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/268:13 pm
SEA
- RFD
1 stop22h 32m
Multiple Airlines
Sun 8/309:35 pm
RFD
- SEA
1 stop15h 00m
Multiple Airlines
Deal found 6/15![Multiple Airlines logo]()
$367
This American Airlines deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/911:56 pm
SEA
- CMI
1 stop9h 11m
American Airlines
Sun 7/126:36 pm
CMI
- SEA
1 stop8h 16m
American Airlines
Deal found 6/16![American Airlines logo]()
$373
This Delta deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/156:00 am
SEA
- MLI
1 stop8h 22m
Delta
Wed 9/235:10 pm
MLI
- SEA
1 stop8h 49m
Delta
Deal found 6/18![Delta logo]()
$349
This Alaska Airlines deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/35:48 pm
SEA
- ORD
Nonstop4h 11m
Alaska Airlines
Tue 8/256:00 am
ORD
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 6/15![Alaska Airlines logo]()
$355
This Southwest deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/305:30 am
SEA
- MDW
Nonstop3h 55m
Southwest
Sat 8/14:50 pm
MDW
- SEA
1 stop9h 25m
Southwest
Deal found 6/17![Southwest logo]()
$365
This United Airlines deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/2711:50 pm
SEA
- PIA
1 stop8h 31m
United Airlines
Sat 10/311:20 pm
PIA
- SEA
1 stop7h 39m
United Airlines
Deal found 6/16![United Airlines logo]()
$371
This Delta deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/810:35 am
SEA
- ORD
Nonstop4h 08m
Delta
Tue 7/145:55 pm
ORD
- SEA
Nonstop4h 39m
Delta
Deal found 6/18![Delta logo]()
$355
This Alaska Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/45:48 pm
SEA
- ORD
Nonstop4h 11m
Alaska Airlines
Sun 8/97:20 am
ORD
- SEA
1 stop7h 43m
Alaska Airlines
Deal found 6/19![Alaska Airlines logo]()
$355
This Southwest deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/318:25 pm
SEA
- MDW
1 stop7h 35m
Southwest
Fri 8/74:00 pm
MDW
- SEA
1 stop10h 20m
Southwest
Deal found 6/19![Southwest logo]()
$368
This Alaska Airlines deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 7/46:00 am
SEA
- ORD
Nonstop4h 03m
Alaska Airlines
Wed 8/266:00 am
ORD
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 6/15![Alaska Airlines logo]()
$355
This Delta deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/77:20 am
SEA
- ORD
Nonstop4h 08m
Delta
Wed 7/85:55 pm
ORD
- SEA
Nonstop4h 39m
Delta
Deal found 6/15![Delta logo]()
$355
This Kiwi.com deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/2211:54 am
SEA
- RFD
2 stops22h 30m
Multiple Airlines
Sun 7/261:14 pm
RFD
- SEA
1 stop23h 25m
Multiple Airlines
Deal found 6/18![Multiple Airlines logo]()
$440
This United Airlines deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/2811:00 pm
SEA
- PIA
1 stop9h 06m
United Airlines
Sun 9/65:45 am
PIA
- SEA
1 stop7h 47m
United Airlines
Deal found 6/18![United Airlines logo]()
$410
This Southwest deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/1011:05 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Tue 8/189:00 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/18![Southwest logo]()
$373
This Delta deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/15:40 pm
SEA
- ORD
Nonstop3h 59m
Delta
Sun 7/56:55 am
ORD
- SEA
Nonstop4h 36m
Delta
Deal found 6/17![Delta logo]()
$355
This Alaska Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/68:48 am
SEA
- ORD
1 stop13h 11m
Alaska Airlines
Sat 9/197:00 pm
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Deal found 6/19![Alaska Airlines logo]()
$358
This Kiwi.com deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/298:13 pm
SEA
- RFD
1 stop14h 11m
Multiple Airlines
Mon 8/39:13 pm
RFD
- SEA
2 stops22h 38m
Multiple Airlines
Deal found 6/15![Multiple Airlines logo]()
$447
This Southwest deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/1011:05 pm
SEA
- MDW
Nonstop3h 55m
Southwest
Tue 7/149:50 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/17![Southwest logo]()
$376
This American Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/210:22 am
SEA
- CMI
1 stop9h 37m
American Airlines
Tue 7/76:36 pm
CMI
- SEA
1 stop8h 16m
American Airlines
Deal found 6/19![American Airlines logo]()
$514
This Delta deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/35:40 pm
SEA
- ORD
Nonstop3h 59m
Delta
Thu 8/275:56 pm
ORD
- SEA
Nonstop4h 39m
Delta
Deal found 6/15![Delta logo]()
$355
This KAYAK deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/95:51 pm
SEA
- ORD
Nonstop4h 08m
Alaska Airlines
Thu 9/102:18 pm
ORD
- SEA
1 stop9h 22m
Alaska Airlines
Deal found 6/18![Alaska Airlines logo]()
$363
This United Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/57:00 am
SEA
- BMI
1 stop7h 38m
United Airlines
Tue 12/86:00 am
BMI
- SEA
1 stop7h 40m
United Airlines
Deal found 6/19![United Airlines logo]()
$443
This Southwest deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/83:00 pm
SEA
- MDW
1 stop7h 10m
Southwest
Wed 7/1511:45 am
MDW
- SEA
2 stops8h 35m
Southwest
Deal found 6/16![Southwest logo]()
$380
This Kiwi.com deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/228:13 pm
SEA
- RFD
1 stop22h 32m
Multiple Airlines
Sun 8/309:35 pm
RFD
- SEA
1 stop15h 00m
Multiple Airlines
Deal found 6/15![Multiple Airlines logo]()
$469
This American Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/93:41 pm
SEA
- SPI
1 stop6h 26m
American Airlines
Mon 9/142:51 pm
SPI
- SEA
1 stop8h 45m
American Airlines
Deal found 6/19![American Airlines logo]()
$525
This Delta deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/67:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Sat 8/89:30 am
ORD
- SEA
1 stop9h 07m
Delta
Deal found 6/17![Delta logo]()
$363
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated June 20, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated June 20, 2026 and is based on user searches.
This Booking.com deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/197:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Mon 6/229:48 pm
ORD
- SEA
1 stop14h 00m
Frontier
Deal found 6/18![Frontier logo]()
$354
This Orbitz deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/2512:17 am
SEA
- ORD
Nonstop4h 03m
Multiple Airlines
Sun 6/287:20 am
ORD
- SEA
1 stop29h 15m
Multiple Airlines
Deal found 6/19![Multiple Airlines logo]()
$353
This American Airlines deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/253:05 pm
SEA
- ORD
Nonstop4h 28m
American Airlines
Wed 7/16:55 am
ORD
- SEA
Nonstop4h 32m
American Airlines
Deal found 6/15![American Airlines logo]()
$356
This Alaska Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/306:00 am
SEA
- ORD
Nonstop4h 03m
Alaska Airlines
Fri 7/35:42 pm
ORD
- SEA
Nonstop4h 39m
Alaska Airlines
Deal found 6/19![Alaska Airlines logo]()
$359
This United Airlines deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/11:55 pm
SEA
- ORD
Nonstop4h 26m
United Airlines
Fri 7/37:00 am
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 6/16![United Airlines logo]()
$355
This Delta deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/15:40 pm
SEA
- ORD
Nonstop3h 59m
Delta
Wed 7/225:55 pm
ORD
- SEA
Nonstop4h 39m
Delta
Deal found 6/19![Delta logo]()
$358
This American Airlines deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/83:28 pm
SEA
- PIA
1 stop6h 54m
American Airlines
Tue 7/146:58 pm
PIA
- SEA
1 stop7h 54m
American Airlines
Deal found 6/15![American Airlines logo]()
$349
This American Airlines deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/92:09 pm
SEA
- MLI
1 stop8h 32m
American Airlines
Mon 7/136:50 pm
MLI
- SEA
1 stop8h 09m
American Airlines
Deal found 6/18![American Airlines logo]()
$349
This Alaska Airlines deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/1312:17 am
SEA
- ORD
Nonstop4h 03m
Alaska Airlines
Wed 7/226:00 am
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Deal found 6/19![Alaska Airlines logo]()
$357
This Kiwi.com deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/155:48 pm
SEA
- ORD
Nonstop4h 11m
Multiple Airlines
Thu 8/208:11 pm
ORD
- SEA
1 stop16h 28m
Multiple Airlines
Deal found 6/19![Multiple Airlines logo]()
$352
This Southwest deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/155:00 am
SEA
- MDW
Nonstop3h 55m
Southwest
Wed 7/299:50 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/15![Southwest logo]()
$355
This American Airlines deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/293:28 pm
SEA
- BMI
1 stop7h 07m
American Airlines
Wed 8/195:00 am
BMI
- SEA
1 stop6h 29m
American Airlines
Deal found 6/18![American Airlines logo]()
$343
One-way flights from Seattle to IllinoisSearch for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated June 20, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated June 20, 2026.
This American Airlines deal was found by Cheapflights users on 6/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 7/46:00 am
SEA
- STL
1 stop8h 48m
American Airlines
Deal found 6/18![American Airlines logo]()
$147
This Kiwi.com deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/58:13 pm
SEA
- STL
1 stop20h 02m
Frontier
Deal found 6/17![Frontier logo]()
$150
This Kiwi.com deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/158:13 pm
SEA
- STL
1 stop20h 02m
Frontier
Deal found 6/19![Frontier logo]()
$151
This Kiwi.com deal was found by Cheapflights users on 6/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/128:13 pm
SEA
- STL
1 stop20h 02m
Frontier
Deal found 6/16![Frontier logo]()
$152
This Trip.com deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/78:13 pm
SEA
- STL
1 stop19h 52m
Frontier
Deal found 6/17![Frontier logo]()
$153
This CheapOair deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/139:16 pm
SEA
- STL
1 stop26h 01m
Frontier
Deal found 6/15![Frontier logo]()
$156
This Kiwi.com deal was found by Cheapflights users on 6/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/147:00 pm
SEA
- STL
1 stop14h 51m
Frontier
Deal found 6/15![Frontier logo]()
$157
This Kiwi.com deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/188:53 pm
SEA
- STL
1 stop18h 57m
Frontier
Deal found 6/19![Frontier logo]()
$159
This Super.com deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/18:13 pm
SEA
- STL
1 stop20h 02m
Frontier
Deal found 6/19![Frontier logo]()
$160
This Super.com deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 7/268:53 pm
SEA
- STL
1 stop19h 22m
Frontier
Deal found 6/17![Frontier logo]()
$161
This Frontier deal was found by Cheapflights users on 6/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/117:00 am
SEA
- STL
1 stop10h 15m
Frontier
Deal found 6/17![Frontier logo]()
$163
This Kiwi.com deal was found by Cheapflights users on 6/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/208:53 pm
SEA
- STL
1 stop19h 12m
Frontier
Deal found 6/19![Frontier logo]()
$165
Find flight deals from Seattle to Illinois
Keep the following information in mind while searching for Seattle to Illinois flight deals. Data was last updated June 20, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $271 (American Airlines) |
One-way from | $147 (American Airlines) |
Popular in | June |
Cheapest in | February |
Average price | $416 |
Good round-trip deal | $378 or less |
Good one-way deal | $199 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Seattle to Illinois that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated June 20, 2026.
Use the filters below to find and compare flights from Seattle to Illinois that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
SeattleMoline
SEA - MLI
SEAMLI
Seattle/Tacoma Intl
Mon 9/7
6:00 am-4:22 pm
1 stop8h 22m
Moline Quad-City
Mon 9/14
5:10 pm-11:59 pm
1 stop8h 49m
$349
SeattleMoline
SEA - MLI
SEAMLI
Seattle/Tacoma Intl
Tue 9/15
6:00 am-4:22 pm
1 stop8h 22m
Moline Quad-City
Wed 9/23
5:10 pm-11:59 pm
1 stop8h 49m
$349
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 7/15
5:48 pm-11:59 pm
Nonstop4h 11m
Chicago O'Hare Intl
Sat 7/25
8:20 pm-11:04 pm
Nonstop4h 44m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Mon 9/14
5:13 pm-11:17 pm
Nonstop4h 04m
Chicago O'Hare Intl
Thu 9/17
8:01 pm-10:45 pm
Nonstop4h 44m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Fri 7/3
5:48 pm-11:59 pm
Nonstop4h 11m
Chicago O'Hare Intl
Tue 8/25
6:00 am-8:30 am
Nonstop4h 30m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 7/8
10:35 am-4:43 pm
Nonstop4h 08m
Chicago O'Hare Intl
Tue 7/14
5:55 pm-8:34 pm
Nonstop4h 39m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 8/4
5:48 pm-11:59 pm
Nonstop4h 11m
Chicago O'Hare Intl
Sun 8/9
7:20 am-1:03 pm
1 stop7h 43m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Sat 7/4
6:00 am-12:03 pm
Nonstop4h 03m
Chicago O'Hare Intl
Wed 8/26
6:00 am-8:30 am
Nonstop4h 30m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 7/7
7:20 am-1:28 pm
Nonstop4h 08m
Chicago O'Hare Intl
Wed 7/8
5:55 pm-8:34 pm
Nonstop4h 39m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 7/1
5:40 pm-11:39 pm
Nonstop3h 59m
Chicago O'Hare Intl
Sun 7/5
6:55 am-9:31 am
Nonstop4h 36m
$355
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Seattle to Illinois
Have a flexible travel schedule? Discover the best time to fly to Illinois from Seattle with our price prediction graph.
SEA-BMI
SEA-MLI
SEA-PIA
SEA-ORD
SEA-MDW
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.
Cheapflights Insights
Everything you need to know about your flight from Seattle to Illinois
SEA-USIL
SEA-BMI
SEA-MLI
SEA-PIA
SEA-ORD
What is the cheapest month to book a flight from Seattle to Illinois?
Currently, January is the cheapest month in which you can book a flight from Seattle to Illinois (average of $47). Flying from Seattle to Illinois in March is currently the most expensive (average of $686). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.
What is the cheapest time of day to fly from SEA to IL?
Find hourly flight availability from Seattle to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated June 20, 2026.
It’s typically best to fly out from Seattle to Illinois at noon. Doing so could potentially save you 5% on the flight price compared to flying in the morning, which is usually more expensive.
Weekly flight availability from Seattle to Illinois
Explore weekly flight availability from Seattle to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated June 20, 2026.
The most flights from SEA to USIL are scheduled on a Friday (67 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (39 on average).
How much does it cost to fly round-trip from Seattle to Illinois?
How far ahead should I book a flight from Seattle to Illinois?
The price you pay for your flight from Seattle to Illinois may vary depending on when you book. For the best chance of a lower fare, look to book 81 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
What is the cheapest day to fly from Seattle to Illinois?
Use this chart to determine the cheapest time to fly round-trip from Seattle to Illinois. Price data was last updated on June 13, 2026.
Travelers seeking maximum savings on their Seattle to Illinois flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Reviews of airlines servicing Illinois
Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated June 20, 2026.
Read through reviews of airlines operating flights from Seattle to Illinois, such as Alaska Airlines,Southwest, andDelta. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Comfort
7.8
Crew
8.5
Food
7.1
Entertainment
7.0
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Jun 2026
SEA - RNO
Boarding
8.1
Comfort
7.8
Crew
8.5
Food
7.1
Entertainment
7.0
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Jun 2026
SEA - RNO
Boarding
8.1
Comfort
7.8
Crew
8.5
Food
7.1
Entertainment
7.0
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Jun 2026
SEA - RNO
Boarding
8.1
Comfort
7.8
Crew
8.5
Food
7.1
Entertainment
7.0
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Jun 2026
SEA - RNO
Boarding
8.1
Comfort
7.8
Crew
8.5
Food
7.1
Entertainment
7.0
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Jun 2026
SEA - RNO
Boarding
8.1
Comfort
7.8
Crew
8.5
Food
7.1
Entertainment
7.0
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Jun 2026
SEA - RNO
Related info for your journey
Find useful and relevant information for your journey from Seattle to Illinois. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
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Alternative routes for Seattle to Illinois
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to Illinois by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Seattle to Illinois by cabin class
Find flights from Seattle to Illinois, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Seattle and Illinois flights
Browse other Seattle and Illinois flight options. Last updated on June 20, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Seattle to Illinois flights
Consider these flights traveling from Seattle to Illinois.
Top 7 airlines flying from Seattle to Illinois
Discover the top 7 airlines that operate flights from Seattle to Illinois. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated June 20, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$118 | Average$349 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$124 | Average$249 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$177 | Average$352 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$177 | Average$439 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$179 | Average$423 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$193 | Average$313 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$207 | Average$362 | FlexibilityNo cancel fee | On-time63% |