$71 Find Cheap Flights from Colorado to Illinois

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Good to know

Low seasonJanuary
High seasonAugust
Cheapest flight$71
Best time to beat the crowds with an average 2% drop in price.
Most popular time to fly and prices are also 15% lower on average.
Flight from Denver to St. Louis

Flights from Colorado to Illinois: the best tips from KAYAK users

Insights shared by verified travelers who flew the route from Colorado to Illinois 
AdamFlew with SouthwestDEN-ORDOct 2024
Arriving T5 at ORD on Southwest is often a LONG walk, with no moving walkways going out, to baggage claim / pickup.
BrianFlew with United AirlinesDEN-ORDJan 2024
Big airport. Make sure you have enough time between flights for rest, eating, etc…

FAQs for booking flights from Colorado to Illinois

  • How does KAYAK find such low prices on flights from Colorado 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 Colorado to Illinois.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Colorado 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 Colorado 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 Colorado 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 Colorado 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 Colorado to Illinois up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • Which is the cheapest airport to fly into in Illinois?

    Prices will differ depending on the departure airport, but generally, the cheapest airport to fly to in Illinois is Bloomington-Normal Airport (BMI), with an average flight price of $79.

  • What is the cheapest day to fly to Illinois?

    Based on KAYAK data, the cheapest day to fly to Illinois is Friday where round-trip tickets can be as cheap as $290. On the other hand, the most expensive day to fly is Sunday, where round-trip prices are $513 on average.

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

    The cheapest time of day to fly to Illinois is generally at night, when round-trip flights cost $183 on average. Morning departures are around 2% cheaper than evening flights, on average. The most expensive time of day to fly to Illinois is generally in the afternoon, which is peak travel time and where the average cost of a ticket is $650.

  • What is the cheapest flight to Illinois?

    The cheapest ticket to Illinois from Colorado found in the last 72 hours was to Peoria, at $46 round-trip. The most popular route is Aspen (ASE) to Chicago O'Hare Intl Airport (ORD) and the cheapest round-trip airline ticket found on this route in the last 72 hours was $120.

  • What is the cheapest month to fly from Colorado to Illinois?

    The cheapest month for flights from Colorado to Illinois is January, when tickets cost $278 (return) on average. On the other hand, the most expensive months are December and July, when the average cost of round-trip tickets is $524 and $469 respectively.

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

    To get a below average price on the flight from Colorado to Illinois, you should book around 3 weeks before departure. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.

  • How long is the flight to Illinois?

    An average nonstop flight from Colorado to Illinois takes 6h 48m, covering a distance of 927 miles. The shortest route is Denver (DEN) to St. Louis (STL) with an average flight time of 2h 00m.

  • What are the most popular destinations in Illinois?

    Based on KAYAK flight searches, the most popular destination is Chicago (81% of total searches to Illinois). The next most popular destinations are St. Louis (14%) and Moline (2%). Searches for flights to Peoria (1%), to Evansville (1%) and to Bloomington (0%) are also popular.

Top 5 airlines serving from Colorado to Illinois

 
Need help choosing which airline to fly with from Colorado 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
SouthwestOverall score based on 4287 reviews
8.2Boarding
8.0Comfort
7.6Entertainment
7.1Food
8.6Crew
Airline reviews

I would have liked to arrive on time - not 5 hours late!

4.0 OkayAnonymous, Apr 2025DEN - SEA
Read more Southwest reviews

I would have liked to arrive on time - not 5 hours late!

1.5 hour delay, poor service, no compassion from the crew. Terrible experience

Our flight was diverted from being a non-stop to getting within 150 miles and requiring another plane. We heard 4 or 5 different versions from SW as to why we had to stop, then wait for a replacement plane. Five hour delay, weather did not come up as a single excuse.... communication was not clear and well explained. No one really took charge!

Flight was awfully bumpy and landing was a bit jolting. I was in the restroom when snacks and drinks were served and was not asked if i wanted any. I had to ask for water finally.

I really like open seating. I hate that I've heard this is going away. This is one of the unique things that makes Southwest my goto choice.

It seems as though the provisions are even less. Although SWA used to be an economy Airline, that isn't really the case anymore. I paid over $700. for a round trip to Denver and I could have flown just about any airline for the price. The drinks are now in a 6-ounce cup and with ice I'm sure a can would fill more than 2 cups. However, I am very proud of SWA for using paper rather than continuing to contribute to the millions of plastic cups being used each day. I've thought of this fr many years and am so glad to see it come to fruition, if not by only SWA so far.

My original flight was extremely delayed but I was able to join the standby list for an earlier flight. I was grateful for this feature but I wish I could’ve gotten my standby confirmation sooner.

I like that it was on time and the staff was friendly.

No space for our carryon and needed to check at plane before boarding !

Flight was ok. Boarding wasn’t fun. Flights were delayed by 12 minutes on each leg.

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

There's just no way to sit fully upright and comfortably in these seats. There needs to be 2 more inches of room, and that's not something that only one person on the flight needs - the whole flight needs 2 more inches of room. If that means you sell 6 less seats, so be it. It's too close for anyone. Forcing people to pay for "premium" economy just to get "barely enough space to breathe" isn't really an answer to that.

The crew were very nice. The Chocolate is good and v there’s no entertainment. Thanks

The crew were very nice. I would have appreciated a pillow for comfort. I had a special meal that was sloppy, but the salad was great. Thanks

Tight! Seats are not designed for those of us who wear extra-large clothes.

The non-stop flight from Grand Rapids was excellent. I neither expected or needed a budget flight and Allegiant made the trip easy and for an affordable price, Arriving at the Mesa Airport (AZA) is a delight compared to the international airport. For our return flight, we were able to arrive 75 minutes before the flight, return the rental car, check our bag and make it to the gate in plenty of time. That would never happen at most airports.

Easiest flights I’ve ever taken. Plane was comfortable without overly crowded seating.

Terrible. Still have not received the refund from them. They sent it to some account that I don't even know. Spoke with costumer service and they are unable to help.

I didn’t like it at all. I miss my second flight because of the delay on Allegiant Air now I m stuck in MCO.

Good, but a bit late on take off after loading. Don't like charging for carry ons!

First time flying with them and will definitely fly again in the future. Crew was so nice and friendly, fought was seamless. They are simple planes, no entertainment, but it’s fine for a short flight or if you have personal devices Rates are competitive, and they did so well with keeping the flight on time after a tropical storm, where other airlines had delays and cancellations.

They boarded passengers that sat in the back of the plane first, making boarding very efficient.

I didn't even take this flight. My plans changed and I couldn't get ahold of customer service and the website kept breaking down during the attempt to change the flight. I wound up taking another airline entirely and eating the cost.

The worst flying experience ever 3 delays. No accommodations. Had to deboard the plane after being delayed.

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.

Per usual, flight status, staff courtesy and professionalism were excellent

Everything was on time, we arrived early, everything worked well.

The only thing is if Wi-Fi is available after you land and taxi to the gate. It takes forever to get to the gate, and having the Wi-Fi continue would be great to bide the time at least 5 minutes before you arrive at the entrance. That is my only comment; otherwise, everything was good.

I never got to experience the flight because they delayed my first flight and I missed this one. Then Frontier didn't want to help me rebook a flight to get me to my final destination.

The Boarding process in Denver was chaotic, and since the line was so long, we were lined up very far from the gate. If there were any announcements from the gate staff, we didn't hear them. The flight attendants were spectacular. The only negative part of the flight was sitting by a 2 1/2 year old who was unruly and unfortunately had parents that matched his behaviors. Also, the restaurants in Denver on the E concourse, they didn't have food (passengers could only order 1 item on the entire menu) or the restaurants had 12-14 people waiting for orders to be prepared and another 6 people waiting to order. If you have a layover in Denver and need to grab food, be prepared to visit the shops with pre-packaged sandwiches, or you can visit another concourse but it may take a while to transit throughout the airport.

The crew was delayed because they came on another flight that was delayed due to weather 10pm flight left at 1.30 am The airline made no effort to align alternate crew

The flight itself was ok and the pilot was very communicative. However, our flight was delayed for almost 3 hours, the gate was changed 3 times and there was no communication as we were waiting. The flight staff was overall a little crabby...I understand as they probably had a long day but we all did.

Everything went as planned. Crew was great. Seats were still not that comfortable.

they delayed my flight which ended up, causing my layover flight to leave without me, resulting in me missing a flight and having to stay overnight in Houston international. I got no compensation other than a flight to my original location only a day later. i’ve never experienced such a unprofessional situation

After waiting several minutes to be acknowledged by 3 employees on their phones, was told we had missed our flight because the doors were closed at that literal moment. Had they given any actual service or help while we were standing there we would have been on with time to spare. More than 10 people were turned away in this fashion claiming there was no way they could let us on the plane, even though it was still sitting connected to the terminal. After the desk agents let us know they didn't care about the situation we were forced to pay more than twice the price of our original tickets as no credits were given for the price of the "missed" flight. And the icing on the cake was after being treated poorly, fleeced for another few hundred dollars for new tickets? We waited on the next plane for 25 minutes passed the "doors closed" time, letting almost an extra dozen passengers on board. You're company has lazy, disinterested employees and your lack of any real help will ensure this was the first and last time we fly Frontier. Awful.

The seats were extremely hard and uncomfortable, even for a budget airline.

Boarding was very well executed. Got my bag right away.

Overall experience good. There was no food and seats were not terribly comfortable.

Book cheap flights from Colorado to Illinois

Recent round-trip flight deals

8/15Fri
nonstopAllegiant Air
2h 00mDEN-PIA
8/18Mon
nonstopAllegiant Air
2h 25mPIA-DEN
$102
8/14Thu
nonstopFrontier
2h 28mDEN-MDW
8/18Mon
nonstopFrontier
2h 44mMDW-DEN
$116
10/23Thu
nonstopAmerican Airlines
2h 48mDEN-ORD
10/25Sat
nonstopAmerican Airlines
2h 38mORD-DEN
$157
8/5Tue
nonstopSouthwest
2h 20mDEN-MDW
8/12Tue
nonstopSouthwest
2h 35mMDW-DEN
$157
8/6Wed
nonstopSouthwest
2h 20mDEN-MDW
8/9Sat
nonstopSouthwest
2h 35mMDW-DEN
$158
8/2Sat
nonstopAmerican Airlines
2h 48mDEN-ORD
8/5Tue
nonstopAmerican Airlines
2h 34mORD-DEN
$177
7/20Sun
nonstopUnited Airlines
2h 35mDEN-ORD
7/22Tue
nonstopUnited Airlines
2h 50mORD-DEN
$189
9/12Fri
1 stopDelta
7h 40mDEN-STL
9/17Wed
1 stopDelta
5h 55mSTL-DEN
$197
9/11Thu
1 stopDelta
7h 40mDEN-STL
9/17Wed
1 stopDelta
8h 39mSTL-DEN
$207
8/14Thu
1 stopUnited Airlines
6h 13mDEN-PIA
8/17Sun
nonstopUnited Airlines
2h 30mPIA-DEN
$219

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Recent one-way flight deals

10/8Wed
1 stopFrontier
8h 08mDEN-STL
$71
8/23Sat
nonstopFrontier
2h 11mDEN-STL
$73
10/11Sat
nonstopAmerican Airlines
2h 50mDEN-ORD
$78
8/13Wed
nonstopUnited Airlines
2h 35mDEN-ORD
$79
8/7Thu
nonstopUnited Airlines
2h 08mDEN-STL
$79
8/27Wed
nonstopSouthwest
2h 20mDEN-MDW
$79
8/9Sat
nonstopSouthwest
2h 25mDEN-MDW
$80
10/15Wed
1 stopAmerican Airlines
7h 09mDEN-STL
$88
6/20Fri
nonstopAllegiant Air
2h 04mDEN-PIA
$92
6/30Mon
nonstopAllegiant Air
2h 04mDEN-PIA
$106

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Last minute flights from Colorado to Illinois

Last minute flight, train and bus deals

6/16Mon
nonstopAllegiant Air
2h 04mDEN-PIA
6/20Fri
nonstopAllegiant Air
2h 18mPIA-DEN
$200
6/13Fri
nonstopFrontier
2h 12mDEN-STL
6/16Mon
nonstopFrontier
2h 27mSTL-DEN
$215
6/16Mon
multi-stopAmerican Airlines
7h 22mDEN-MLI
6/17Tue
multi-stopAmerican Airlines
7h 23mMLI-DEN
$229
6/13Fri
multi-stopAmerican Airlines
5h 12mDEN-MLI
6/16Mon
multi-stopAmerican Airlines
7h 36mMLI-DEN
$259
6/13Fri
nonstopUnited Airlines
2h 18mDEN-PIA
7/25Fri
multi-stopUnited Airlines
6h 57mPIA-DEN
$319
6/16Mon
multi-stopDelta
5h 54mDEN-ORD
6/24Tue
multi-stopDelta
7h 18mORD-DEN
$328
6/13Fri
multi-stopUnited Airlines
6h 02mDEN-PIA
7/25Fri
multi-stopUnited Airlines
6h 57mPIA-DEN
$329
6/17Tue
nonstopSouthwest
2h 25mDEN-MDW
6/18Wed
nonstopSouthwest
2h 35mMDW-DEN
$337
6/17Tue
nonstopSouthwest
2h 25mDEN-MDW
6/18Wed
multi-stopSouthwest
4h 15mMDW-DEN
$347
6/16Mon
multi-stopDelta
5h 54mDEN-ORD
6/18Wed
multi-stopDelta
4h 58mORD-DEN
$357

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Everything you need to know for your flight to Illinois

Cabin class types available on flights to Colorado

Cabin classes available on flights to Colorado. Prices are the lowest found on KAYAK over the last 7 days. Price and availability is not guaranteed.

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