$70+ 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 5/8. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Apr 8 — Apr 151
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 March 9, 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 March 9, 2026.
This American Airlines deal was found by Cheapflights users on 3/6. 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 4/1811:16 am
SEA
- ORD
Nonstop4h 30m
American Airlines
Tue 4/217:30 am
ORD
- SEA
Nonstop4h 44m
American Airlines
Deal found 3/6![American Airlines logo]()
$180
This Southwest deal was found by Cheapflights users on 3/7. 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.
Sat 4/2511:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Wed 4/2910:15 am
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/7![Southwest logo]()
$180
This Kiwi.com deal was found by Cheapflights users on 3/5. 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 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Frontier
Tue 4/217:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/5![Frontier logo]()
$181
This Southwest deal was found by Cheapflights users on 3/8. 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.
Sat 4/185:45 am
SEA
- ORD
1 stop6h 35m
Southwest
Sat 4/253:05 pm
ORD
- SEA
1 stop9h 05m
Southwest
Deal found 3/8![Southwest logo]()
$183
This Kiwi.com deal was found by Cheapflights users on 3/5. 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.
Thu 4/167:12 pm
SEA
- ORD
1 stop12h 38m
Frontier
Tue 4/2110:45 am
ORD
- SEA
2 stops24h 42m
Frontier
Deal found 3/5![Frontier logo]()
$188
This Southwest deal was found by Cheapflights users on 3/8. 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.
Sat 4/185:45 am
SEA
- MDW
2 stops9h 45m
Southwest
Sat 4/251:55 pm
MDW
- SEA
1 stop6h 20m
Southwest
Deal found 3/8![Southwest logo]()
$188
This United Airlines deal was found by Cheapflights users on 3/6. 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 4/187:00 am
SEA
- ORD
Nonstop4h 12m
United Airlines
Sun 4/199:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/6![United Airlines logo]()
$190
This Kiwi.com deal was found by Cheapflights users on 3/4. 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.
Thu 4/3010:57 am
SEA
- ORD
1 stop10h 30m
Multiple Airlines
Sat 5/27:21 pm
ORD
- SEA
1 stop24h 36m
Multiple Airlines
Deal found 3/4![Multiple Airlines logo]()
$191
This Booking.com deal was found by Cheapflights users on 3/5. 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.
Sat 4/1810:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Tue 4/217:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/5![Frontier logo]()
$192
This Delta deal was found by Cheapflights users on 3/6. 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 4/237:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Tue 4/286:00 pm
ORD
- SEA
Nonstop4h 43m
Delta
Deal found 3/6![Delta logo]()
$197
This Southwest deal was found by Cheapflights users on 3/6. 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.
Sat 4/1811:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Mon 4/209:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/6![Southwest logo]()
$197
This American Airlines deal was found by Cheapflights users on 3/7. 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.
Mon 3/3012:13 am
SEA
- ORD
Nonstop4h 16m
American Airlines
Sat 4/48:20 pm
ORD
- SEA
Nonstop4h 44m
American Airlines
Deal found 3/7![American Airlines logo]()
$198
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 March 9, 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 March 9, 2026.
This Delta deal was found by Cheapflights users on 3/7. 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 5/57:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Wed 5/67:15 am
ORD
- SEA
Nonstop4h 49m
Delta
Deal found 3/7![Delta logo]()
$199
This United Airlines deal was found by Cheapflights users on 3/6. 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.
Thu 4/1611:59 pm
SEA
- ORD
Nonstop4h 00m
United Airlines
Sun 4/199:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/6![United Airlines logo]()
$207
This Southwest deal was found by Cheapflights users on 3/8. 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.
Sat 3/285:00 am
SEA
- MDW
Nonstop3h 55m
Southwest
Tue 3/319:20 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 3/8![Southwest logo]()
$214
This Alaska Airlines deal was found by Cheapflights users on 3/8. 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 4/255:57 pm
SEA
- STL
Nonstop4h 02m
Alaska Airlines
Sun 4/267:00 am
STL
- SEA
Nonstop4h 32m
Alaska Airlines
Deal found 3/8![Alaska Airlines logo]()
$297
This American Airlines deal was found by Cheapflights users on 3/8. 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 4/223:17 pm
SEA
- PIA
1 stop6h 16m
American Airlines
Mon 4/277:05 pm
PIA
- SEA
1 stop7h 31m
American Airlines
Deal found 3/8![American Airlines logo]()
$300
This Delta deal was found by Cheapflights users on 3/6. 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 4/287:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Tue 4/287:10 pm
ORD
- SEA
1 stop6h 49m
Delta
Deal found 3/6![Delta logo]()
$207
This United Airlines deal was found by Cheapflights users on 3/6. 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 4/811:59 pm
SEA
- ORD
Nonstop4h 00m
United Airlines
Sun 4/199:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/6![United Airlines logo]()
$207
This Southwest deal was found by Cheapflights users on 3/5. 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 4/3011:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sun 5/39:40 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/5![Southwest logo]()
$217
This Kiwi.com deal was found by Cheapflights users on 3/5. 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.
Fri 3/206:24 pm
SEA
- RFD
2 stops16h 39m
Multiple Airlines
Wed 3/258:20 pm
RFD
- SEA
1 stop26h 43m
Multiple Airlines
Deal found 3/5![Multiple Airlines logo]()
$477
This Southwest deal was found by Cheapflights users on 3/6. 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.
Tue 3/315:30 am
SEA
- MDW
Nonstop3h 50m
Southwest
Fri 4/39:55 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 3/6![Southwest logo]()
$217
This United Airlines deal was found by Cheapflights users on 3/8. 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.
Sun 4/2611:59 pm
SEA
- STL
1 stop6h 26m
United Airlines
Fri 5/17:09 pm
STL
- SEA
1 stop6h 50m
United Airlines
Deal found 3/8![United Airlines logo]()
$229
This Delta deal was found by Cheapflights users on 3/6. 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 4/21:32 pm
SEA
- STL
1 stop8h 49m
Delta
Tue 4/72:12 pm
STL
- SEA
1 stop6h 18m
Delta
Deal found 3/6![Delta logo]()
$229
This Southwest deal was found by Cheapflights users on 3/7. 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 4/302:50 pm
SEA
- MDW
1 stop7h 05m
Southwest
Mon 5/49:50 pm
MDW
- SEA
1 stop12h 50m
Southwest
Deal found 3/7![Southwest logo]()
$222
This Delta deal was found by Cheapflights users on 3/4. 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 4/2711:14 pm
SEA
- STL
1 stop8h 28m
Delta
Fri 5/15:35 pm
STL
- SEA
1 stop8h 19m
Delta
Deal found 3/4![Delta logo]()
$229
This Alaska Airlines deal was found by Cheapflights users on 3/6. 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.
Thu 5/288:45 am
SEA
- STL
1 stop5h 52m
Alaska Airlines
Mon 6/17:41 pm
STL
- SEA
Nonstop4h 31m
Alaska Airlines
Deal found 3/6![Alaska Airlines logo]()
$307
This Southwest deal was found by Cheapflights users on 3/6. 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 4/206:15 pm
SEA
- MDW
2 stops9h 10m
Southwest
Mon 4/279:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/6![Southwest logo]()
$232
This American Airlines deal was found by Cheapflights users on 3/8. 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 6/1611:58 pm
SEA
- CMI
1 stop9h 12m
American Airlines
Tue 6/236:44 pm
CMI
- SEA
1 stop6h 55m
American Airlines
Deal found 3/8![American Airlines logo]()
$318
This Southwest deal was found by Cheapflights users on 3/7. 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.
Sat 5/26:40 am
SEA
- STL
2 stops9h 30m
Southwest
Fri 5/156:00 pm
STL
- SEA
1 stop8h 55m
Southwest
Deal found 3/7![Southwest logo]()
$234
This Delta deal was found by Cheapflights users on 3/8. 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 4/35:30 am
SEA
- STL
1 stop5h 47m
Delta
Mon 4/66:12 pm
STL
- SEA
1 stop7h 51m
Delta
Deal found 3/8![Delta logo]()
$264
This American Airlines deal was found by Cheapflights users on 3/6. 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.
Fri 3/2712:13 am
SEA
- BMI
1 stop8h 48m
American Airlines
Sat 4/43:45 pm
BMI
- SEA
1 stop9h 24m
American Airlines
Deal found 3/6![American Airlines logo]()
$329
This Alaska Airlines deal was found by Cheapflights users on 3/4. 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 6/59:59 pm
SEA
- ORD
1 stop13h 23m
Alaska Airlines
Sun 6/77:59 pm
ORD
- SEA
1 stop15h 26m
Alaska Airlines
Deal found 3/4![Alaska Airlines logo]()
$335
This Southwest deal was found by Cheapflights users on 3/8. 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.
Tue 6/26:00 am
SEA
- MDW
Nonstop4h 00m
Southwest
Sat 6/69:00 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/8![Southwest logo]()
$239
This United Airlines deal was found by Cheapflights users on 3/5. 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 4/82:39 pm
SEA
- PIA
1 stop6h 18m
United Airlines
Wed 4/152:50 pm
PIA
- SEA
1 stop9h 52m
United Airlines
Deal found 3/5![United Airlines logo]()
$329
This Alaska Airlines deal was found by Cheapflights users on 3/8. 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 8/228:55 am
SEA
- STL
1 stop6h 18m
Alaska Airlines
Sun 8/306:41 am
STL
- SEA
Nonstop4h 31m
Alaska Airlines
Deal found 3/8![Alaska Airlines logo]()
$347
This American Airlines deal was found by Cheapflights users on 3/4. 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 5/73:17 pm
SEA
- MLI
1 stop6h 37m
American Airlines
Sun 5/106:40 pm
MLI
- SEA
1 stop7h 56m
American Airlines
Deal found 3/4![American Airlines logo]()
$354
This Southwest deal was found by Cheapflights users on 3/8. 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 5/1511:05 am
SEA
- MDW
1 stop8h 30m
Southwest
Tue 5/197:30 am
MDW
- SEA
2 stops12h 30m
Southwest
Deal found 3/8![Southwest logo]()
$242
This Delta deal was found by Cheapflights users on 3/6. 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 4/25:30 am
SEA
- STL
1 stop5h 47m
Delta
Thu 4/97:15 am
STL
- SEA
1 stop7h 12m
Delta
Deal found 3/6![Delta logo]()
$294
This United Airlines deal was found by Cheapflights users on 3/6. 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 3/2811:59 pm
SEA
- PIA
1 stop8h 03m
United Airlines
Sat 4/41:20 pm
PIA
- SEA
1 stop7h 26m
United Airlines
Deal found 3/6![United Airlines logo]()
$329
This Delta deal was found by Cheapflights users on 3/6. 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 4/1411:14 pm
SEA
- ORD
1 stop9h 05m
Delta
Mon 4/207:15 am
ORD
- SEA
Nonstop4h 49m
Delta
Deal found 3/6![Delta logo]()
$297
This Southwest deal was found by Cheapflights users on 3/8. 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 6/41:50 pm
SEA
- MDW
1 stop8h 05m
Southwest
Sat 6/64:50 pm
MDW
- SEA
1 stop9h 20m
Southwest
Deal found 3/8![Southwest logo]()
$259
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated March 9, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated March 9, 2026 and is based on user searches.
This American Airlines deal was found by Cheapflights users on 3/7. 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.
Mon 3/3012:13 am
SEA
- ORD
Nonstop4h 16m
American Airlines
Sat 4/48:20 pm
ORD
- SEA
Nonstop4h 44m
American Airlines
Deal found 3/7![American Airlines logo]()
$198
This Kiwi.com deal was found by Cheapflights users on 3/5. 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 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Frontier
Tue 4/217:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/5![Frontier logo]()
$181
This Kiwi.com deal was found by Cheapflights users on 3/5. 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.
Thu 4/167:12 pm
SEA
- ORD
1 stop12h 38m
Frontier
Tue 4/2110:45 am
ORD
- SEA
2 stops24h 42m
Frontier
Deal found 3/5![Frontier logo]()
$188
This American Airlines deal was found by Cheapflights users on 3/6. 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 4/1811:16 am
SEA
- ORD
Nonstop4h 30m
American Airlines
Tue 4/217:30 am
ORD
- SEA
Nonstop4h 44m
American Airlines
Deal found 3/6![American Airlines logo]()
$180
This Southwest deal was found by Cheapflights users on 3/8. 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.
Sat 4/185:45 am
SEA
- ORD
1 stop6h 35m
Southwest
Sat 4/253:05 pm
ORD
- SEA
1 stop9h 05m
Southwest
Deal found 3/8![Southwest logo]()
$183
This Southwest deal was found by Cheapflights users on 3/8. 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.
Sat 4/185:45 am
SEA
- MDW
2 stops9h 45m
Southwest
Sat 4/251:55 pm
MDW
- SEA
1 stop6h 20m
Southwest
Deal found 3/8![Southwest logo]()
$188
This Delta deal was found by Cheapflights users on 3/8. 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.
Sat 4/187:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Tue 4/217:35 am
ORD
- SEA
1 stop9h 11m
Delta
Deal found 3/8![Delta logo]()
$190
This Booking.com deal was found by Cheapflights users on 3/5. 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.
Sat 4/1810:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Tue 4/217:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/5![Frontier logo]()
$192
This Southwest deal was found by Cheapflights users on 3/6. 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.
Sat 4/1811:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Mon 4/209:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/6![Southwest logo]()
$197
This Southwest deal was found by Cheapflights users on 3/7. 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.
Sat 4/2511:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Wed 4/2910:15 am
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/7![Southwest logo]()
$180
This Kiwi.com deal was found by Cheapflights users on 3/4. 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.
Thu 4/3010:57 am
SEA
- ORD
1 stop10h 30m
Multiple Airlines
Sat 5/27:21 pm
ORD
- SEA
1 stop24h 36m
Multiple Airlines
Deal found 3/4![Multiple Airlines logo]()
$191
This Delta deal was found by Cheapflights users on 3/6. 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 4/305:59 pm
SEA
- ORD
Nonstop3h 59m
Delta
Tue 5/57:15 am
ORD
- SEA
Nonstop4h 49m
Delta
Deal found 3/6![Delta logo]()
$197
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 March 9, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated March 9, 2026.
This Kiwi.com deal was found by Cheapflights users on 3/6. 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.
Fri 5/86:57 pm
SEA
- STL
1 stop22h 15m
Frontier
Deal found 3/6![Frontier logo]()
$70
This Kiwi.com deal was found by Cheapflights users on 3/4. 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 4/158:07 pm
SEA
- STL
1 stop21h 14m
Frontier
Deal found 3/4![Frontier logo]()
$82
This Kiwi.com deal was found by Cheapflights users on 3/6. 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.
Sun 5/37:12 pm
SEA
- STL
1 stop22h 20m
Frontier
Deal found 3/6![Frontier logo]()
$89
This Kiwi.com deal was found by Cheapflights users on 3/4. 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 5/510:42 am
SEA
- ORD
1 stop10h 45m
Multiple Airlines
Deal found 3/4![Multiple Airlines logo]()
$90
This Kiwi.com deal was found by Cheapflights users on 3/4. 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.
Fri 5/110:06 pm
SEA
- ORD
1 stop29h 19m
Multiple Airlines
Deal found 3/4![Multiple Airlines logo]()
$91
This Kiwi.com deal was found by Cheapflights users on 3/5. 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.
Thu 4/164:20 pm
SEA
- ORD
1 stop15h 30m
Frontier
Deal found 3/5![Frontier logo]()
$93
This Kiwi.com deal was found by Cheapflights users on 3/6. 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.
Thu 5/74:20 pm
SEA
- STL
1 stop24h 52m
Frontier
Deal found 3/6![Frontier logo]()
$93
This Kiwi.com deal was found by Cheapflights users on 3/4. 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 4/207:12 pm
SEA
- MDW
2 stops25h 02m
Frontier
Deal found 3/4![Frontier logo]()
$94
This Expedia deal was found by Cheapflights users on 3/4. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/159:35 pm
SEA
- ORD
1 stop7h 12m
Frontier
Deal found 3/4![Frontier logo]()
$95
This Kiwi.com deal was found by Cheapflights users on 3/6. 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.
Thu 5/710:42 am
SEA
- MDW
2 stops26h 07m
Frontier
Deal found 3/6![Frontier logo]()
$95
This Kiwi.com deal was found by Cheapflights users on 3/4. 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.
Fri 5/17:12 pm
SEA
- STL
1 stop22h 20m
Frontier
Deal found 3/4![Frontier logo]()
$95
This Southwest deal was found by Cheapflights users on 3/8. 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.
Sat 4/189:00 am
SEA
- ORD
2 stops12h 25m
Southwest
Deal found 3/8![Southwest logo]()
$97
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 March 9, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $180 (Delta) |
One-way from | $66 (Kiwi.com) |
Popular in | December |
Cheapest in | February |
Average price | $338 |
Good round-trip deal | $311 or less |
Good one-way deal | $180 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 March 9, 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
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 5/5
7:15 am-1:23 pm
Nonstop4h 08m
Chicago O'Hare Intl
Wed 5/6
7:15 am-10:04 am
Nonstop4h 49m
$199
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Thu 4/16
11:59 pm-5:59 am
Nonstop4h 00m
Chicago O'Hare Intl
Sun 4/19
9:54 pm-12:34 am
Nonstop4h 40m
$207
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 4/28
7:15 am-1:23 pm
Nonstop4h 08m
Chicago O'Hare Intl
Tue 4/28
7:10 pm-11:59 pm
1 stop6h 49m
$207
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 4/8
11:59 pm-5:59 am
Nonstop4h 00m
Chicago O'Hare Intl
Sun 4/19
9:54 pm-12:34 am
Nonstop4h 40m
$207
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Sat 3/28
5:00 am-10:55 am
Nonstop3h 55m
Chicago Midway
Tue 3/31
9:20 pm-11:55 pm
Nonstop4h 35m
$214
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Thu 4/30
11:55 pm-5:55 am
Nonstop4h 00m
Chicago Midway
Sun 5/3
9:40 pm-12:10 am
Nonstop4h 30m
$217
Quickest round-trip
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Tue 3/31
5:30 am-11:20 am
Nonstop3h 50m
Chicago Midway
Fri 4/3
9:55 pm-12:30 am
Nonstop4h 35m
$217
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Thu 4/30
2:50 pm-11:55 pm
1 stop7h 05m
Chicago Midway
Mon 5/4
9:50 pm-8:40 am
1 stop12h 50m
$222
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Sun 4/26
11:59 pm-8:25 am
1 stop6h 26m
Lambert-St Louis
Fri 5/1
7:09 pm-11:59 pm
1 stop6h 50m
$229
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Thu 4/2
1:32 pm-12:21 am
1 stop8h 49m
Lambert-St Louis
Tue 4/7
2:12 pm-6:30 pm
1 stop6h 18m
$229
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-STL
SEA-ORD
SEA-MDW
SEA-PIA
SEA-RFD
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-STL
SEA-ORD
SEA-MDW
SEA-PIA
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 $93). Flying from Seattle to Illinois in March is currently the most expensive (average of $177). 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 March 9, 2026.
It’s typically best to fly out from Seattle to Illinois in the evening. Doing so could potentially save you 6% on the flight price compared to flying in the morning, which is usually more expensive.
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 February 21, 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.
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 March 9, 2026.
The most flights from SEA to USIL are scheduled on a Monday (41 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (20 on average).
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 March 9, 2026.
Read through reviews of airlines operating flights from Seattle to Illinois, such as Alaska Airlines, Delta, and Hawaiian Airlines. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Comfort
7.8
Crew
8.5
Food
7.1
Overall
8.0
Boarding
8.1
Entertainment
7.0
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Comfort
7.8
Crew
8.5
Food
7.1
Overall
8.0
Boarding
8.1
Entertainment
7.0
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Comfort
7.8
Crew
8.5
Food
7.1
Overall
8.0
Boarding
8.1
Entertainment
7.0
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Comfort
7.8
Crew
8.5
Food
7.1
Overall
8.0
Boarding
8.1
Entertainment
7.0
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Comfort
7.8
Crew
8.5
Food
7.1
Overall
8.0
Boarding
8.1
Entertainment
7.0
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Comfort
7.8
Crew
8.5
Food
7.1
Overall
8.0
Boarding
8.1
Entertainment
7.0
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
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
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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 March 9, 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 March 9, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$111 | Average$288 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$114 | Average$262 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$162 | Average$288 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$166 | Average$397 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$169 | Average$313 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$177 | Average$339 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$177 | Average$444 | FlexibilityNo cancel fee | On-time71% |