$84+ Cheap flights from Washington 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 4/15. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Apr 15 — Apr 221
Round-trip
1 adult, Economy
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Cheapest flights from Washington to IllinoisExplore the most affordable flight options available from Washington to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 16, 2026.
Explore the most affordable flight options available from Washington to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 16, 2026.
This United Airlines deal was found by Cheapflights users on 3/11. 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 4/173:48 pm
SEA
- ORD
1 stop6h 42m
United Airlines
Wed 4/228:00 pm
ORD
- SEA
Nonstop4h 42m
United Airlines
Deal found 3/11![United Airlines logo]()
$199
This Southwest deal was found by Cheapflights users on 3/11. 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 4/226:40 pm
SEA
- MDW
1 stop9h 20m
Southwest
Thu 4/239:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/11![Southwest logo]()
$199
This Southwest deal was found by Cheapflights users on 3/11. 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 4/255:45 am
SEA
- ORD
1 stop6h 35m
Southwest
Tue 4/2810:30 am
ORD
- SEA
1 stop8h 25m
Southwest
Deal found 3/11![Southwest logo]()
$202
This Kissandfly.com deal was found by Cheapflights users on 3/14. 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 Kissandfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/2810:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Tue 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Deal found 3/14![Frontier logo]()
$204
This WAYA deal was found by Cheapflights users on 3/12. 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 WAYA is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/1112:42 pm
SEA
- ORD
1 stop9h 56m
Multiple Airlines
Sat 4/186:00 am
ORD
- SEA
Nonstop4h 37m
Multiple Airlines
Deal found 3/12![Multiple Airlines logo]()
$206
This Kiwi.com deal was found by Cheapflights users on 3/12. 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 4/1810:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Wed 4/227:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/12![Frontier logo]()
$208
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 4/139:34 pm
SEA
- ORD
1 stop30h 34m
Frontier
Mon 4/206:31 pm
ORD
- SEA
2 stops40h 56m
Frontier
Deal found 3/13![Frontier logo]()
$209
This Frontier deal was found by Cheapflights users on 3/15. 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 Frontier 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 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Deal found 3/15![Frontier logo]()
$210
This Booking.com deal was found by Cheapflights users on 3/11. 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.
Thu 4/2310:57 am
SEA
- ORD
1 stop17h 23m
Frontier
Tue 4/287:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/11![Frontier logo]()
$211
This Booking.com deal was found by Cheapflights users on 3/13. 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 4/2411:07 am
SEA
- ORD
1 stop16h 43m
Frontier
Sat 5/27:21 pm
ORD
- SEA
1 stop24h 36m
Frontier
Deal found 3/13![Frontier logo]()
$212
This Trip.com deal was found by Cheapflights users on 3/12. 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.
Sat 4/255:42 pm
SEA
- ORD
Nonstop4h 17m
Alaska Airlines
Tue 4/286:00 am
ORD
- SEA
Nonstop4h 32m
Alaska Airlines
Deal found 3/12![Alaska Airlines logo]()
$214
This Southwest deal was found by Cheapflights users on 3/11. 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 4/157:10 pm
SEA
- MDW
1 stop8h 35m
Southwest
Wed 4/224:00 pm
MDW
- SEA
2 stops9h 55m
Southwest
Deal found 3/11![Southwest logo]()
$214
Best flights from Washington to IllinoisDiscover carefully curated flight deals from Washington to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated March 16, 2026.
Discover carefully curated flight deals from Washington to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated March 16, 2026.
This United Airlines deal was found by Cheapflights users on 3/11. 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 4/242:39 pm
SEA
- ORD
Nonstop4h 11m
United Airlines
Thu 4/309:20 pm
ORD
- SEA
Nonstop4h 39m
United Airlines
Deal found 3/11![United Airlines logo]()
$217
This Southwest deal was found by Cheapflights users on 3/11. 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 4/1411:40 am
SEA
- STL
2 stops9h 35m
Southwest
Wed 4/225:30 am
STL
- SEA
2 stops14h 30m
Southwest
Deal found 3/11![Southwest logo]()
$225
This Delta deal was found by Cheapflights users on 3/12. 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 4/95:55 pm
SEA
- ORD
Nonstop3h 57m
Delta
Mon 4/137:15 am
ORD
- SEA
Nonstop4h 49m
Delta
Deal found 3/12![Delta logo]()
$227
This Alaska Airlines deal was found by Cheapflights users on 3/12. 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 4/141:35 pm
PDX
- STL
1 stop8h 24m
Alaska Airlines
Wed 4/157:00 am
STL
- PDX
1 stop7h 35m
Alaska Airlines
Deal found 3/12![Alaska Airlines logo]()
$257
This Delta deal was found by Cheapflights users on 3/11. 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 4/2211:15 pm
PDX
- ORD
1 stop6h 46m
Delta
Sat 4/255:04 pm
ORD
- PDX
1 stop6h 38m
Delta
Deal found 3/11![Delta logo]()
$227
This Southwest deal was found by Cheapflights users on 3/15. 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 4/226:00 am
SEA
- MDW
Nonstop4h 00m
Southwest
Wed 4/2910:15 am
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/15![Southwest logo]()
$237
This United Airlines deal was found by Cheapflights users on 3/12. 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 4/3011:55 pm
PDX
- STL
1 stop8h 53m
United Airlines
Mon 5/45:59 pm
STL
- PDX
1 stop6h 55m
United Airlines
Deal found 3/12![United Airlines logo]()
$252
This Southwest deal was found by Cheapflights users on 3/11. 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 5/116:15 pm
SEA
- MDW
2 stops9h 10m
Southwest
Fri 5/156:25 pm
MDW
- SEA
1 stop8h 15m
Southwest
Deal found 3/11![Southwest logo]()
$242
This United Airlines deal was found by Cheapflights users on 3/14. 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 4/1811:59 pm
PDX
- ORD
Nonstop4h 04m
United Airlines
Sat 4/259:08 am
ORD
- PDX
Nonstop4h 36m
United Airlines
Deal found 3/14![United Airlines logo]()
$271
This Southwest deal was found by Cheapflights users on 3/12. 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 4/232:50 pm
SEA
- STL
1 stop7h 25m
Southwest
Sat 4/2510:35 am
STL
- SEA
2 stops9h 20m
Southwest
Deal found 3/12![Southwest logo]()
$248
This Delta deal was found by Cheapflights users on 3/11. 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 5/111:15 pm
PDX
- ORD
1 stop6h 46m
Delta
Tue 5/57:10 pm
ORD
- PDX
1 stop6h 43m
Delta
Deal found 3/11![Delta logo]()
$277
This Alaska Airlines deal was found by Cheapflights users on 3/14. 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 5/27:41 pm
GEG
- ORD
1 stop8h 59m
Alaska Airlines
Wed 5/66:00 am
ORD
- GEG
1 stop9h 23m
Alaska Airlines
Deal found 3/14![Alaska Airlines logo]()
$306
This Southwest deal was found by Cheapflights users on 3/14. 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
- STL
2 stops10h 25m
Southwest
Tue 4/215:30 am
STL
- SEA
2 stops14h 30m
Southwest
Deal found 3/14![Southwest logo]()
$253
This United Airlines deal was found by Cheapflights users on 3/11. 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 4/17:00 am
SEA
- ORD
Nonstop4h 12m
United Airlines
Tue 4/77:40 am
ORD
- SEA
1 stop9h 06m
United Airlines
Deal found 3/11![United Airlines logo]()
$279
This Alaska Airlines deal was found by Cheapflights users on 3/11. 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 8/223:35 pm
GEG
- ORD
1 stop6h 06m
Alaska Airlines
Thu 8/276:00 am
ORD
- GEG
1 stop8h 30m
Alaska Airlines
Deal found 3/11![Alaska Airlines logo]()
$309
This Delta deal was found by Cheapflights users on 3/12. 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 4/226:05 pm
PDX
- STL
2 stops13h 37m
Delta
Tue 4/286:45 pm
STL
- PDX
1 stop7h 08m
Delta
Deal found 3/12![Delta logo]()
$296
This United Airlines deal was found by Cheapflights users on 3/11. 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 5/218:45 am
SEA
- STL
1 stop7h 32m
United Airlines
Sun 5/245:10 am
STL
- SEA
1 stop6h 50m
United Airlines
Deal found 3/11![United Airlines logo]()
$292
This Delta deal was found by Cheapflights users on 3/12. 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 4/216:05 pm
PDX
- STL
2 stops13h 37m
Delta
Wed 4/296:45 pm
STL
- PDX
1 stop7h 08m
Delta
Deal found 3/12![Delta logo]()
$296
This Southwest deal was found by Cheapflights users on 3/11. 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 4/227:00 am
GEG
- STL
1 stop8h 40m
Southwest
Wed 4/296:35 am
STL
- GEG
2 stops9h 10m
Southwest
Deal found 3/11![Southwest logo]()
$282
This Alaska Airlines deal was found by Cheapflights users on 3/11. 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 8/167:41 pm
GEG
- ORD
1 stop7h 21m
Alaska Airlines
Wed 8/197:00 am
ORD
- GEG
1 stop6h 42m
Alaska Airlines
Deal found 3/11![Alaska Airlines logo]()
$346
This Delta deal was found by Cheapflights users on 3/12. 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 4/225:30 am
PDX
- STL
2 stops16h 55m
Delta
Wed 4/296:45 pm
STL
- PDX
1 stop7h 08m
Delta
Deal found 3/12![Delta logo]()
$296
This United Airlines deal was found by Cheapflights users on 3/11. 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 4/67:37 pm
SEA
- ORD
1 stop7h 50m
United Airlines
Fri 4/109:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/11![United Airlines logo]()
$316
This Southwest deal was found by Cheapflights users on 3/11. 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 4/259:00 am
SEA
- ORD
2 stops12h 25m
Southwest
Sat 5/26:15 am
ORD
- SEA
2 stops14h 00m
Southwest
Deal found 3/11![Southwest logo]()
$289
This Delta deal was found by Cheapflights users on 3/12. 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.
Sun 3/294:55 pm
SEA
- STL
1 stop5h 26m
Delta
Thu 4/26:12 pm
STL
- SEA
1 stop7h 51m
Delta
Deal found 3/12![Delta logo]()
$299
This United Airlines deal was found by Cheapflights users on 3/12. 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 5/44:15 pm
PDX
- ORD
1 stop6h 43m
United Airlines
Sun 5/108:00 pm
ORD
- PDX
Nonstop4h 35m
United Airlines
Deal found 3/12![United Airlines logo]()
$317
This Southwest deal was found by Cheapflights users on 3/11. 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 4/181:35 pm
PDX
- ORD
1 stop6h 45m
Southwest
Mon 4/207:20 pm
ORD
- PDX
1 stop7h 35m
Southwest
Deal found 3/11![Southwest logo]()
$299
This Delta deal was found by Cheapflights users on 3/11. 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 4/1610:42 am
PDX
- STL
2 stops11h 43m
Delta
Sat 4/187:00 am
STL
- PDX
1 stop7h 17m
Delta
Deal found 3/11![Delta logo]()
$302
This Alaska Airlines deal was found by Cheapflights users on 3/12. 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 5/71:34 pm
GEG
- STL
1 stop8h 25m
Alaska Airlines
Sat 5/94:46 pm
STL
- GEG
1 stop8h 25m
Alaska Airlines
Deal found 3/12![Alaska Airlines logo]()
$406
This United Airlines deal was found by Cheapflights users on 3/15. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/1611:59 pm
PDX
- STL
1 stop6h 26m
United Airlines
Sat 4/189:16 am
STL
- PDX
2 stops10h 29m
United Airlines
Deal found 3/15![United Airlines logo]()
$317
This Delta deal was found by Cheapflights users on 3/11. 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 4/307:32 pm
PDX
- STL
2 stops11h 14m
Delta
Tue 5/56:45 pm
STL
- PDX
1 stop7h 08m
Delta
Deal found 3/11![Delta logo]()
$302
Last-minute flights from Washington to IllinoisDiscover last-minute flight deals from Washington to Illinois. Data last updated March 16, 2026 and is based on user searches.
Discover last-minute flight deals from Washington to Illinois. Data last updated March 16, 2026 and is based on user searches.
This WAYA deal was found by Cheapflights users on 3/12. 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 WAYA is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/1112:42 pm
SEA
- ORD
1 stop9h 56m
Multiple Airlines
Sat 4/186:00 am
ORD
- SEA
Nonstop4h 37m
Multiple Airlines
Deal found 3/12![Multiple Airlines logo]()
$206
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 4/139:34 pm
SEA
- ORD
1 stop30h 34m
Frontier
Mon 4/206:31 pm
ORD
- SEA
2 stops40h 56m
Frontier
Deal found 3/13![Frontier logo]()
$209
This Frontier deal was found by Cheapflights users on 3/15. 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 Frontier 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 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Deal found 3/15![Frontier logo]()
$210
This United Airlines deal was found by Cheapflights users on 3/11. 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 4/173:48 pm
SEA
- ORD
1 stop6h 42m
United Airlines
Wed 4/228:00 pm
ORD
- SEA
Nonstop4h 42m
United Airlines
Deal found 3/11![United Airlines logo]()
$199
This Kiwi.com deal was found by Cheapflights users on 3/12. 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 4/1810:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Wed 4/227:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/12![Frontier logo]()
$208
This Southwest deal was found by Cheapflights users on 3/11. 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 4/226:40 pm
SEA
- MDW
1 stop9h 20m
Southwest
Thu 4/239:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/11![Southwest logo]()
$199
This Southwest deal was found by Cheapflights users on 3/11. 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 4/226:50 am
SEA
- MDW
2 stops8h 05m
Southwest
Sun 4/269:40 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/11![Southwest logo]()
$204
This Booking.com deal was found by Cheapflights users on 3/11. 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.
Thu 4/2310:57 am
SEA
- ORD
1 stop17h 23m
Frontier
Tue 4/287:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/11![Frontier logo]()
$211
This Booking.com deal was found by Cheapflights users on 3/13. 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 4/2411:07 am
SEA
- ORD
1 stop16h 43m
Frontier
Sat 5/27:21 pm
ORD
- SEA
1 stop24h 36m
Frontier
Deal found 3/13![Frontier logo]()
$212
This Southwest deal was found by Cheapflights users on 3/11. 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 4/255:45 am
SEA
- ORD
1 stop6h 35m
Southwest
Tue 4/2810:30 am
ORD
- SEA
1 stop8h 25m
Southwest
Deal found 3/11![Southwest logo]()
$202
This Trip.com deal was found by Cheapflights users on 3/12. 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.
Sat 4/255:42 pm
SEA
- ORD
Nonstop4h 17m
Alaska Airlines
Tue 4/286:00 am
ORD
- SEA
Nonstop4h 32m
Alaska Airlines
Deal found 3/12![Alaska Airlines logo]()
$214
This Kissandfly.com deal was found by Cheapflights users on 3/14. 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 Kissandfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/2810:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Tue 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Deal found 3/14![Frontier logo]()
$204
One-way flights from Washington to IllinoisSearch for one-way flight options from Washington to Illinois. Find affordable one-way fares based on user searches. Data last updated March 16, 2026.
Search for one-way flight options from Washington to Illinois. Find affordable one-way fares based on user searches. Data last updated March 16, 2026.
This Kiwi.com deal was found by Cheapflights users on 3/12. 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 3/12![Frontier logo]()
$84
This Kiwi.com deal was found by Cheapflights users on 3/12. 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 4/1512:28 pm
PDX
- STL
1 stop28h 53m
Frontier
Deal found 3/12![Frontier logo]()
$84
This Kiwi.com deal was found by Cheapflights users on 3/15. 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.
Fri 4/177:12 pm
SEA
- STL
1 stop22h 20m
Frontier
Deal found 3/15![Frontier logo]()
$89
This American Airlines deal was found by Cheapflights users on 3/11. 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 5/63:17 pm
SEA
- STL
1 stop6h 29m
American Airlines
Deal found 3/11![American Airlines logo]()
$91
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 4/1011:58 am
PDX
- STL
1 stop19h 50m
Frontier
Deal found 3/13![Frontier logo]()
$94
This Kiwi.com deal was found by Cheapflights users on 3/12. 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 5/87:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 3/12![Frontier logo]()
$95
This Kiwi.com deal was found by Cheapflights users on 3/11. 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 3/11![Frontier logo]()
$98
This Kiwi.com deal was found by Cheapflights users on 3/15. 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.
Tue 4/1410:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Deal found 3/15![Frontier logo]()
$99
This CheapOair deal was found by Cheapflights users on 3/11. 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 5/1910:37 am
PDX
- STL
Nonstop4h 00m
Alaska Airlines
Deal found 3/11![Alaska Airlines logo]()
$99
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 5/911:37 am
SEA
- ORD
1 stop15h 48m
Multiple Airlines
Deal found 3/13![Multiple Airlines logo]()
$100
This Kiwi.com deal was found by Cheapflights users on 3/11. 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 5/812:35 pm
PDX
- STL
1 stop28h 48m
Frontier
Deal found 3/11![Frontier logo]()
$100
This Kiwi.com deal was found by Cheapflights users on 3/12. 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 5/127:50 pm
SEA
- MDW
2 stops16h 22m
Frontier
Deal found 3/12![Frontier logo]()
$101
Find flight deals from Washington to Illinois
Keep the following information in mind while searching for Washington to Illinois flight deals. Data was last updated March 16, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $199 (United Airlines) |
One-way from | $84 (Kiwi.com) |
Popular in | December |
Cheapest in | February |
Average price | $341 |
Good round-trip deal | $297 or less |
Good one-way deal | $177 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Washington 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 16, 2026.
Use the filters below to find and compare flights from Washington to Illinois that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Fri 4/24
2:39 pm-8:50 pm
Nonstop4h 11m
Chicago O'Hare Intl
Thu 4/30
9:20 pm-11:59 pm
Nonstop4h 39m
$217
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Tue 4/14
11:40 am-11:15 pm
2 stops9h 35m
Lambert-St Louis
Wed 4/22
5:30 am-6:00 pm
2 stops14h 30m
$225
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Thu 4/9
5:55 pm-11:52 pm
Nonstop3h 57m
Chicago O'Hare Intl
Mon 4/13
7:15 am-10:04 am
Nonstop4h 49m
$227
PortlandChicago
PDX - ORD
PDXORD
Portland
Wed 4/22
11:15 pm-8:01 am
1 stop6h 46m
Chicago O'Hare Intl
Sat 4/25
5:04 pm-9:42 pm
1 stop6h 38m
$227
Quickest round-trip
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Wed 4/22
6:00 am-12:00 pm
Nonstop4h 00m
Chicago Midway
Wed 4/29
10:15 am-12:45 pm
Nonstop4h 30m
$237
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Mon 5/11
6:15 pm-5:25 am
2 stops9h 10m
Chicago Midway
Fri 5/15
6:25 pm-12:40 am
1 stop8h 15m
$242
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Thu 4/23
2:50 pm-12:15 am
1 stop7h 25m
Lambert-St Louis
Sat 4/25
10:35 am-5:55 pm
2 stops9h 20m
$248
PortlandSt. Louis
PDX - STL
PDXSTL
Portland
Thu 4/30
11:55 pm-10:48 am
1 stop8h 53m
Lambert-St Louis
Mon 5/4
5:59 pm-10:54 pm
1 stop6h 55m
$252
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Sat 4/18
5:45 am-6:10 pm
2 stops10h 25m
Lambert-St Louis
Tue 4/21
5:30 am-6:00 pm
2 stops14h 30m
$253
PortlandSt. Louis
PDX - STL
PDXSTL
Portland
Tue 4/14
1:35 pm-11:59 pm
1 stop8h 24m
Lambert-St Louis
Wed 4/15
7:00 am-12:35 pm
1 stop7h 35m
$257
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Washington to Illinois
Have a flexible travel schedule? Discover the best time to fly to Illinois from Washington with our price prediction graph.
SEA-STL
PDX-STL
SEA-ORD
SEA-MDW
GEG-STL
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 Washington to Illinois
USWA-USIL
SEA-STL
PDX-STL
SEA-ORD
SEA-MDW
What is the cheapest month to book a flight from State of Washington to Illinois?
Currently, January is the cheapest month in which you can book a flight from State of Washington to Illinois (average of $93). Flying from State of Washington 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 WA to IL?
Find hourly flight availability from Washington 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 16, 2026.
When flying from State of Washington to Illinois, the time of day you fly usually plays a role in the price. Save by searching for a flight in the afternoon, which can drop the price by up to 15% versus a flight in the evening.
What is the cheapest day to fly from State of Washington to Illinois?
Use this chart to determine the cheapest time to fly round-trip from Washington to Illinois. Price data was last updated on March 14, 2026.
Travelers seeking maximum savings on their State of Washington to Illinois flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday evenings flights should be avoided if possible as fares are typically the most expensive at this time.
Weekly flight availability from State of Washington to Illinois
Explore weekly flight availability from Washington 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 16, 2026.
The most flights from USWA to USIL are scheduled on a Sunday (37 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (25 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 16, 2026.
Get a feel of what it's like to fly with Southwest,Alaska Airlines, andDelta from Washington to Illinois by reading reviews from past customers. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Entertainment
7.5
Overall
8.0
Comfort
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Entertainment
7.5
Overall
8.0
Comfort
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Entertainment
7.5
Overall
8.0
Comfort
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Entertainment
7.5
Overall
8.0
Comfort
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Entertainment
7.5
Overall
8.0
Comfort
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Entertainment
7.5
Overall
8.0
Comfort
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Related info for your journey
Find useful and relevant information for your journey from Washington 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 Washington 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 Washington to Illinois by cabin class
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Washington and Illinois flights
Browse other Washington and Illinois flight options. Last updated on March 16, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Find a return flight route from Illinois
Find the right flight back to Washington after your stay in Illinois
Washington to Illinois flights
Consider these flights traveling from Washington to Illinois.
Top 7 airlines flying from Washington to Illinois
Discover the top 7 airlines that operate flights from Washington 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 16, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$108 | Average$349 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$114 | Average$258 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$162 | Average$288 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$164 | Average$397 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$169 | Average$409 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$177 | Average$341 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$177 | Average$412 | FlexibilityNo cancel fee | On-time71% |