$78 Find Cheap Flights from Seattle to Illinois

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Seattle to Illinois departing on 8/30. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy

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These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Illinois.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Illinois.
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Cheap Flights from Seattle to Illinois

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Chicago
Chicagononstop$153
Moline
Moline1 stop$289
Peoria
Peoria1 stop$270
Bloomington
Bloomington1 stop$315
Champaign
Champaign1 stop$284
Springfield
Springfield1 stop$343
Decatur
Decatur1 stop$384
St. Louis
St. Louis1 stop$174
Chicago
Chicagononstop$153
Moline
Moline1 stop$289
Peoria
Peoria1 stop$270
Bloomington
Bloomington1 stop$315
Champaign
Champaign1 stop$284
Springfield
Springfield1 stop$343
Decatur
Decatur1 stop$384
St. Louis
St. Louis1 stop$174

Book Cheap Seattle to Illinois Plane Tickets

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Seattle to Illinois that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Seattle to Illinois

Sat, Aug 30 - Sat, Sep 6
Hawaiian Airlines Logo
5:55 pm - 11:59 pmSEA-ORD
4h 04mnonstop
Hawaiian Airlines Logo
7:00 am - 2:26 pmORD-SEA
9h 26m1 stop
$153Hawaiian Airlines
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Sat, Aug 30 - Sat, Sep 6
Hawaiian Airlines Logo
5:55 pm - 11:59 pmSEA-ORD
4h 04mnonstop
Hawaiian Airlines Logo
3:20 pm - 5:52 pmORD-SEA
4h 32mnonstop
$154Hawaiian Airlines
Find Deal
Wed, Sep 3 - Fri, Sep 5
United Airlines Logo
7:00 am - 3:44 pmSEA-STL
6h 44m1 stop
United Airlines Logo
5:49 pm - 10:59 pmSTL-SEA
7h 10m1 stop
$174United Airlines
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Tue, Aug 26 - Tue, Sep 2
Delta Logo
5:30 am - 1:30 pmSEA-STL
6h 00m1 stop
Delta Logo
7:35 am - 2:43 pmSTL-SEA
9h 08m1 stop
$177Delta
Find Deal
Mon, Aug 25 - Tue, Aug 26
Alaska Airlines Logo
12:59 am - 7:03 amSEA-ORD
4h 04mnonstop
Alaska Airlines Logo
10:00 am - 12:34 pmORD-SEA
4h 34mnonstop
$183Alaska Airlines
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Wed, Aug 20 - Fri, Aug 22
Delta Logo
5:30 am - 1:29 pmSEA-STL
5h 59m1 stop
Delta Logo
5:30 pm - 11:54 pmSTL-SEA
8h 24m1 stop
$183Delta
Find Deal
Tue, Aug 26 - Wed, Aug 27
Alaska Airlines Logo
5:55 pm - 11:59 pmSEA-ORD
4h 04mnonstop
Alaska Airlines Logo
6:20 am - 8:50 amORD-SEA
4h 30mnonstop
$189Alaska Airlines
Find Deal
Thu, Sep 25 - Mon, Oct 6
American Airlines Logo
3:00 pm - 11:48 pmSEA-STL
6h 48m1 stop
American Airlines Logo
10:10 am - 4:53 pmSTL-SEA
8h 43m1 stop
$189American Airlines
Find Deal
Tue, Sep 9 - Sat, Sep 27
United Airlines Logo
8:00 am - 6:25 pmSEA-ORD
8h 25m1 stop
United Airlines Logo
1:08 pm - 3:45 pmORD-SEA
4h 37mnonstop
$195United Airlines
Find Deal
Tue, Dec 30 - Mon, Jan 5
American Airlines Logo
1:22 am - 7:25 amSEA-ORD
4h 03mnonstop
American Airlines Logo
9:45 am - 12:35 pmORD-SEA
4h 50mnonstop
$202American Airlines
Find Deal
Booking Insights

KAYAK's insights & trends for Seattle to Illinois flights

Get data-powered insights and trends into flights from Seattle to Illinois to help you find the cheapest flights, the best time to fly and much more.

What is the cheapest Seattle to Illinois flight route?

The cheapest price for flight routes found by users searching on KAYAK in the last 2 weeks for round-trip flights from Seattle to Illinois.

The cheapest ticket to Illinois from Seattle found in the last 72 hours was to Chicago, at $179 round-trip. The most popular route is from Seattle (SEA) to Chicago O'Hare Intl Airport (ORD), and the cheapest round-trip airline ticket found on this route in the last 72 hours was $187.

Can I save money by flying with a layover from Seattle to Illinois?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

No, with an average price for the route of $547, prices are generally cheapest when you fly direct.

What is the cheapest month to fly from Seattle to Illinois?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Seattle to Illinois, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Seattle to Illinois is January, when tickets cost $223 (return) on average. On the other hand, the most expensive months are December and July, when the average cost of round-trip tickets is $373 and $333 respectively.

What’s the cheapest day of the week to fly from Seattle to Illinois?

The average price of all round-trip flights from Seattle to Illinois clicked on KAYAK for each day over the last 12 months.

For Seattle to Illinois, Wednesday is the cheapest day to fly on average and Sunday is the most expensive. Flying from Illinois back to Seattle, the best deals are generally found on Wednesday, with Sunday being the most expensive.

How far in advance should I book a flight from Seattle to Illinois?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Seattle to Illinois, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Seattle to Illinois, you should book around 4 weeks before departure, which saves you about 48% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 9 weeks before departure.


Good to know

Low seasonJanuary
Cheapest flight$78
Best time to beat the crowds with an average 22% drop in price.
Most popular time to fly and prices are also 11% lower on average.
Flight from Seattle to Chicago O'Hare Airport

FAQs - booking Illinois flights

  • How does KAYAK find such low prices on flights from Seattle to Illinois?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Seattle to Illinois.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Seattle to Illinois?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Seattle to Illinois is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Seattle to Illinois?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly from Seattle to Illinois with an airline and back with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Seattle to Illinois?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying from Seattle to Illinois up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • What is the cheapest time of day to fly to Illinois?

    The cheapest time of day to fly to Illinois is generally in the evening, when round-trip flights cost $288 on average. Morning departures are around 59% more expensive than evening flights, on average. The most expensive time of day to fly to Illinois is generally in the morning, which is peak travel time and where the average cost of a ticket is $458.

Top tips for finding cheap flights to Illinois

  • Looking for a cheap flight? 25% of our users found tickets from Seattle to the following destinations at these prices or less: Chicago $196 one-way - $292 round-trip

Reviews of the top 5 airlines serving from Seattle to Illinois

 
See real verified KAYAK customer reviews for airlines flying from Seattle to Illinois. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Seattle to Illinois? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
Alaska AirlinesOverall score based on 10000 reviews
7.1Entertainment
8.1Boarding
7.8Comfort
8.5Crew
7.1Food
Airline reviews

I was in the middle seat in the last row but that wasn’t their fault. It is why I rated the flight as mediocre, also the landing was a little rough. The good was really good. The self service luggage belt at SEATAC stopped working right when I reached it. I was literally placing my bag on the small belt when the main belt stopped. I understand that it wasn’t just Alaska but the entire side of the terminal. It took the agents about 20 minutes to arrive at a game plan and it certainly wasn’t flawless but they arranged for our luggage to be taken to the plane the old fashioned way by hand. Understandably, the plane was late in leaving. The flight took the proper amount of time and instead of arriving at OAK at 1:45, we got there at 2:30. I took my time getting to baggage claim because I knew it would be late if it was there at all. Sure enough it wasn’t but there was an agent there to greet me and inform me about my luggage. Long story longer, they delivered my luggage to where I was staying which was an hour away from the airport. Alaska has instituted a delivery type tracking system through my email that kept me informed of where my luggage was the whole time. WELL DONE!!

8.0 ExcellentMichael, Jul 2025SEA - OAK
Read more Alaska Airlines reviews

I was in the middle seat in the last row but that wasn’t their fault. It is why I rated the flight as mediocre, also the landing was a little rough. The good was really good. The self service luggage belt at SEATAC stopped working right when I reached it. I was literally placing my bag on the small belt when the main belt stopped. I understand that it wasn’t just Alaska but the entire side of the terminal. It took the agents about 20 minutes to arrive at a game plan and it certainly wasn’t flawless but they arranged for our luggage to be taken to the plane the old fashioned way by hand. Understandably, the plane was late in leaving. The flight took the proper amount of time and instead of arriving at OAK at 1:45, we got there at 2:30. I took my time getting to baggage claim because I knew it would be late if it was there at all. Sure enough it wasn’t but there was an agent there to greet me and inform me about my luggage. Long story longer, they delivered my luggage to where I was staying which was an hour away from the airport. Alaska has instituted a delivery type tracking system through my email that kept me informed of where my luggage was the whole time. WELL DONE!!

Crew was very friendly. Our bags showed up at the carousel within 20 minutes of arrival.

Flight was delayed and hour due to tire issue. First flight of the day, this issue should have been discovered prior to boarding.

Both legs of the trip were delayed about an hour. Planes were new, liked the WiFi availability and entertainment available. Crew was very good. People were happy and helpful. Liked the pilots - they provided updates throughout the flights. Snacks were underwhelming. Drinks were good! Like the smaller sodas and they actually came through the cabin 2x which was great. In Seattle airport the construction caused much confusion for Alaska. Process of printing own tags, etc was chaotic for people who didn’t check in online prior to arrival which in turn caused issues for those who did. Plus airport gates were too small for the number of people flying.

We did have to wait an hour for the runway to be cleared but other than that it was fine.

My seat row didn’t have tray tables which made it pretty difficult to get comfortable on a four hour flight. Good experience outside of that, though.

There was no sitting place in Sea-Tac airport. Even airline didn’t provide any food or dinner. I will never take this airline in my future travel.

Crew was very rude and uncaring. When someone tried to place their bag in overhead bin and they asked for help, crew told them they could not assist. Crew member then told the customer if they couldn’t place into overhead bin on their own, they should have checked in bag. When other customer helped to place the bag in the overhead bin, they were given evil look by crew member and told to hurry back to their uncomfortable middle seat. This was despite the fact that the plane did not leave until 30 minutes later. The flight was ~80% full; when final people boarded, they were forced into middle seats with no room for comfort. There were a handful of emergency row seats unoccupied. When asked if any of the emergency row seats may be used, the crew said that they would cost extra. Normally if a flight is completely boarded and there are open seats, the crew at least gives thought to asking someone if they want to re-locate to the more comfortable seat, especially on a long flight.

I am always uncomfortable about the boarding process. I think every airlines has their own procedures for boarding but all of their procedures are inconvenient because it takes too much time to board. If you board people from back seat to front, I think you can reduce the time to boarding.

Our original fluffy was cancelled. Our substitute flight didn't fly. We lost out on our hotel and car rental. Had to fly out the next morning. Alaska didn't give us any meaningful information. The first flight was scheduled to leave at 4pm and the substitute flight at 9pm. We left the airport at midnight for a hotel. No weather. Beyond disappointed.

southwest just starting charging for luggage. hadnt realized it until it was too late. now out $70 when i couldve bought a carry on if i wouldve known. free bags was one of the only reasons i chose southwest over another airline (the other being no assigned seats, which is apparently also being changed). stupid business decision. wont be flying southwest anymore.

The quality of Southwest Airlines continues to degrade each time I fly with them. If it were not for the free luggage, I would probably choose another airline. Their prices are a little bit competitive, but way too high for the quality of the service. Southwest is not unique in this way. Domestic flight in the United States of America has continued to be a lower and lower quality product. Very sad when you compare the quality of domestic airlines to that of many international airlines around the world.

Very smooth checking in our luggage with a super pleasant SW agent. I enjoyed a fun entertaining movie.

WiFi did not work. For as outrageous as these flights cost, when they’re advertised with certain services/ features they should be in working order

Worst experience I had on Southwest. Still better than most, but the seating was barely tolerable.

The Southwest employees (all two of them) were very nice and cheerful despite the fact the line to self-check a bag (simply drop it off) was hundreds of people long. Thank God I arrived early to the airport because I stood in this line for at least an hour. Once on the flight that had been delayed by an hour, we had no Wi-Fi and thus no entertainment. Finally, I hope the investor strong arm tactics against Southwest pay off in a short-term windfall to your C-Suite because the rest of you are screwed. I have been a faithful Southwest customer for 15 years due to everything you just got rid of. I'm flying to Idaho and Washington in October, both places I used to simply book with Southwest without a second thought now with Frontier (Washington) and United (Idaho) because they offer everything the "new" Southwest does but cheaper and at better times, destinations, etc. This really makes me sad...

It was okay. The plane was delayed from earlier in the day, but they kept updating the departure time, sometimes later, sometimes earlier. That was stressful. Once we finally got on and took off, it was fine. I was supposed to have a connection in Chicago to Los Angeles, and the time for so late I was rebooked to arrive in LA 3 hours late. The departure time to Chicago later became early enough to have taken my original connection and arrive earlier but that wasn't an option.

It was one and half hour late... Not sure if any other experience matters.

Delayed flight. Nicest crew member was a SW pilot flying seated next to me who kindly move to seat the final passenger. Flight extra delayed. My cup of refreshment of ginger ale was so packed with ice it was literally 2 sips.

For my birthday trip this was my second time ever flying, this trip was the best.

Delayed and took off even later than the scheduled delay time

For a 69 year old with health problems I had the worse experience, no wheelchair when I entered a lady told me to sit and wait while a gentleman told me I had to walk to the Delta station, which I did. I had a carry on and a bag, and I was traveling with my service dog, which was on his carrier and the lady charged me for my carry on luggage, beside all the waiting cause of the delay, I had to walk to get my luggage cause no wheelchair showed up, I am so disappointed. I will get in touch with the company. I got home at 3:00 am, not good for my health situation.

Great experience on Delta. Staff from baggage check to flight attendants were very courteous and professional. My only issue was a personal preference for pretzels instead of the chips and cookies that were offered.

There was no problems, just a little uncomfortable with seats that do not lay back a little

Always good but we must do something about people in rows ahead of you that don't put their seats back up when they are suppose to. And It's rough to not be able to even lean over to get something out of my purse.

Flight was delayed, 30+ bags had to be gate checked. Crew were very friendly!

Everything was good until we were boarding our connection flight in Atlanta, we were told to gate check our carry-on, but when we got inside the plane, there was plenty of room in the overhead.

Did not know my son and I had different seating arrangements. He was fine, but it was disappointing.

Flight was canceled, and no effort was made to help with rebooking, no hotel vouchers, no car transportation and minimal food voucher and most places for food were closed by the time the voucher was given. Waited for 3 hours for bags. Simply the worst travel experience I have ever had

Food was surprisingly good but the WiFi was not great

Weather delay in Chicago?. No sense of urgency to make connection in Chicago for our connecting flight that wasn't delayed. Connection was missed.

Overall it was good. I missed my connection but I was put on another flight.

Overall a very poor experience - booked premium economy tickets but due to last minute flight delays , all my itinery went for a toss and had to fly economy class with no access to lounge or any compensation by united airlines to make up for the flight delays . i had expected better experience than that from united.

It was fine, definitely older planes with no charging or anything. There’s no entertainment set up on board, but it is nice that they allow you to access the in flight entertainment from your phone without having to pay for the Wi-Fi and they do offer free texting.

I liked that the flight was nonstop from ORD to CIU for $200 round trip.

The schedule to Moline changed 5 times. The gate changed 6 times. That is a pathetic way to run an airline. No wonder that no one in our company flies on United Express to or from Moline. Changes happen most of the time. I learned my lesson on this trip…never again!

While the staff was pleasant and helpful, the following observations are for your awareness. There was some delay on the tarmac on take off and landing. The paid lunch/food offerings were limited. Entertainment was only available on WiFi at a cost.

The first flight was better in terms of the aircraft.

Smooth flight. Boarding was chaotic. Could not hear the gate agent over the intercom. People were lined up in the wrong lines. Groups one and two were told to board through line one and group 3 through line 2. All very confusing. Once in the air, the flight was smooth. There was no entertainment option on this aircraft, even though it was a larger aircraft.

Overall poor for me I paid extra for seats with leg room and my regional flights exit row seats have less leg room then the others that's money that could have been saved and on my final flight home the flights air was not operating it was unbearably hot in the cabin I will be contacting United and filing a DOT complaint

Couldn’t get the door on the plane to close leading to a nearly 2 hour delay. But, hey at least they didn’t cancel the flight.

The flight was fine and the crew awesome. The problem is ORD and AA. Computers went down, ORD fell apart and a 40 min flight turned into a 3 hour trip. Guess the answer is to not try and fly to ORD after noon. But, as I said, crew was awesome and did everything they could to lesson the flight time.

The flight was fine but the 8 hour delay in Chicago was awful - 5 gate changes and repeated delays without an explanation. No vouchers. Nothing.

Most miserable flight ever. We waited almost 2 hours on the runway because the flight was oversold. American offered $1200 credit. Then there was some nonsense about weight distribution. Ridiculous. No food for 8 plus hours on the flight. I will be writing a letter.

The flight was 2 hour delayed, otherwise everything was excellent. The delay was due to the hourly limit requirement so given that as a reason, I'm happy with the flight!

Not sure the logic of the boarding in Groups. I was loaded first on the aisle. Then the guy in the middle. Then the guy by the window. Constantly holding up the other people boarding behind them with us blocking the aisle and this happened in most of the other rows

To start, I’d like to say that every American Airline personnel I interacted with on the ground, especially flight crew, was very friendly and did their best to help me out. Despite this, however, my experience with the airline was an entire mess. The 7:19 PM flight was heavily delayed due to weather, and pushed to 10:30 AM the next morning. Because of this, I had to spend the night inside of the airport. At some point later in the night, I got an email saying that the flight had been canceled. I called the support number, and the representative on the other line told me that the flight was still on and that I didn’t need to rebook. The next morning, no one came to the gate to open the door for the crew until almost 11 AM. By this time the flight crew had been waiting for over an hour, and they had called management to get someone to open the door for them multiple times. Around 11:30, the gate screen had changed to a different flight. I ended up buying a last minute ticket with Southwest airline just to get to Chicago, because the next flight with American wasn’t until 7:19 pm that day. Now, earlier that morning my suitcase had been sent ahead of me to ORD. I went to baggage claim to ask them if I could have my suitcase forwarded to where I was staying. The representative at SDF baggage claim said they could and put the claim in for me. As I was going back through TSA, I got an email that the airline had found my suitcase, but the next step was to send it BACK to SDF. I called the airline support number again, and I made it clear that my suitcase needed to stay in Chicago and to not come back to SDF. The representative told me that they would hold my suitcase at ORD and that it wasn’t going to be forwarded anywhere. Once I got there, I found that they had loaded my suitcase onto a plane to send it back to SDF. Thankfully, I had gotten to the baggage claim counter in time for them to put in a request to bring my suitcase back up. My refund with the airline is processing already, but because of this entire experience and miscommunication at every turn of the way, I will not book with American Airlines in the future.

The plane was late and then sat on the runway for almost 45 minutes before taking off.

Crew professional. Easy bag drop off. On time. Good entertainment.

Everything was great. Boarding, early departure, early arrival, and deplaning were smooth. Smooth flight.

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