$27 Find Cheap Flights from Colorado to Illinois

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1 adult, Economy, 0 bags

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Good to know

Low seasonJanuary
Cheapest flight$27
Best time to beat the crowds with an average 4% drop in price.
Most popular time to fly and prices are also 5% 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 Southwest
DEN
-
ORD
Oct 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 Airlines
DEN
-
ORD
Jan 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 airlines fly most frequently to Illinois?

    Colorado and Illinois are connected by different airlines. The airlines that fly that route the most regularly are United Airlines (143 flights per week), Air Canada (84 flights per week), and American Airlines (82 flights per week).

  • How many airports are there in Illinois?

    There are 12 airports in Illinois. The busiest airport is Chicago O'Hare Airport (ORD), with 91% of all flights arriving there.

  • 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 Chicago O'Hare Intl Airport (ORD), with an average flight price of $234.

  • What is the cheapest day to fly to Illinois?

    Based on KAYAK data, the cheapest day to fly to Illinois is Thursday where round-trip tickets can be as cheap as $295. On the other hand, the most expensive day to fly is Sunday, where round-trip prices are $510 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 $216 on average. Morning departures are around 2% more expensive 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 $544.

  • What is the cheapest flight to Illinois?

    The cheapest ticket to Illinois from Colorado found in the last 72 hours was to Peoria, at $63 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 $182.

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

    The cheapest month for flights from Colorado to Illinois is November, when tickets cost $294 (return) on average. On the other hand, the most expensive months are September and February, when the average cost of round-trip tickets is $494 and $490 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 4 weeks before departure, which saves you about 45% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.

  • How many cities have direct flights to Illinois?

    From Colorado, there are direct flights to Illinois from 6 cities. The city with the most direct flights is Denver, with 537 direct flights each week.

  • How many direct flights to Illinois are there each day?

    There are around 90 direct flights from within Colorado to Illinois every day. Most flights (60%) depart in the morning.

  • How many direct flights to Illinois are there each week?

    Each week there are around 626 direct flights from within Colorado to Illinois. The most common day for departures is Sunday, with 19% of flights taking off on this day.

  • How long is the flight to Illinois?

    An average nonstop flight from Colorado to Illinois takes 6h 27m, covering a distance of 927 miles. The shortest route is Denver (DEN) to St. Louis (STL) with an average flight time of 1h 58m.

  • How many long-haul flights are there to Illinois each week?

    There are not any long-haul (6-12 hour flight duration) or medium-haul (3-6 hour flight duration) flights to Illinois. Instead, there are 626 short-haul flights (up to 3 hour flight duration), with the most arriving from Denver.

  • 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 (15%) and Moline (2%). Searches for flights to Peoria (1%), to Evansville (0%) and to Bloomington (0%) are also popular.

Reviews of the 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 4335 reviews
7.5Entertainment
8.1Boarding
7.0Food
8.6Crew
8.0Comfort
Airline reviews

It was as expected and I was grateful for the wheel chair help and ease of use.

10.0 ExcellentAnonymous, Apr 2026
LAS - PDX
Read more Southwest reviews

It was as expected and I was grateful for the wheel chair help and ease of use.

One of the best airlines for fast boarding, on time arrivals, and top notch service!

Love them will get a Southwest card to track my points and keep flying with them. My family and I were pleased with the services.

WiFi was not working and didn’t have a beverage service

My flight from Denver to Minneapolis was excellent. My flight from Minneapolis to Denver was one of the worst I flights I have ever experienced. I had a window seat, the gentleman in the middle seat was morbidly obese and SW should have made him purchase two seats. His elbow dug into my arm most of the way even after I asked to please be careful. I was literally squashed between the him and the window with no wiggle room. The plane was full so it was not possible to ask for a different seat. I realize I should have complained to the flight attendant but I didn't feel anything could be done to rectify the situation. I fly SW often, I will continue to do so as this was my first negative experience.

All good except once again bags took an hour at Midway Airport Happens all the time. Ridiculous

Everything went smoothly and we even arrived a little bit early.

The seats were comfortable, and the boarding process was pretty smooth.

It was rough. The staff was unprofessional, the choice of on board drinks terrible, it was cramped in space at every airport, they always ran out of overhead bin space so they pressured people to check bags for free or we couldn’t leave on the plane— so I did check my bag to help, and they nearly lost my bag. My bag did not arrive on the luggage belt, another man on my flight and I had to waste our time going to the baggage office to search for our bags. I would only fly southwest again if it was my last choice. Also, my flights were consistently delayed over and over again— at one point they straight up told us we were waiting for the pilot to arrive.

Connecting flight is on time and boarding was a breeze!

Very comfortable flight, snacks and drinks were good, good communication from crew. Could have used a little more information on timing of boarding for group 5

Great flight. Got to watch a movie. Smooth flight and early arrival at ORD.

It was better than excellent. The staff in Mason City were great. The young woman that pushed my wheelchair did more than could be expected of her. She came from India 17 years ago. I don't remember her name.

After arriving in Chicago, we were taxiing for 1.5 hours with infrequent and untruthful updates about the amount of time it would take to arrive at the gate. Minimally, the team could have provided timing expectations that were more truthful, especially one their original expectations were not met.

Every staff member was professional, friendly and courteous. The pizza twist was ok. It was warm but too much dough.

I had a terrible experience. My flight got delayed from Atlanta to Chicago on Monday April 6, 2026, and that led to me missing my next flight to Brussels. United Airlines didn’t provide me with any accommodation for shelter. I had to sleep at the airport in Chicago. The next flight I was put on didn’t leave until the evening hours of Tuesday 4/7/2026.

The flight was officially delayed 3 times, and was actually later than that. Combined, it was a 3 hour delay, but there was no recognition (miles, voucher, etc). The crew seemed stressed. The captain sounded nervous in his announcements. The flight itself was smooth and uneventful.

Just a bad day to fly. Flight was delayed from scheduled 6:50 pm departure to 8:50 pm. Combination of factors mostly related to weather at the destination airport (which is where the incoming flight originated) which delayed the inbound flight over an hour. Once on board, we taxied but had to hold again on the taxiway for 10 minutes or so. We did not get wheels up until after 9 pm. The flight was smooth but about 18 minutes from our destination, we had to hold for several minutes more due to weather at ORD. We finally landed at ORD about 11:08 pm (accounting for the time difference, that was about a 3 hour delay from our scheduled departure time). It felt like we were never going to get to our destination. But the flight crew and attendants were very good. The movie selection onboard was also very nice. Got to watch half of a movie just during our taxi from the gate at ATL due to the delay!

3 hour delay…. Nearly 2 hours sitting on tarmac. Do better, United. Or at least have the sense to not say “we hope you enjoyed your flight with us” upon disembarking.

Flights were on time. Free Wifi on plane. Everything was well organized.

just had water and there was plenty of leg & seat room. But then i don't weight 220#s!!

Not totally their fault- screaming kids that had zero parent intervention.

It was cold on the flight. The crew was very pleasant. I didn't order any food. We were delayed due to Captain waiting on maintenance log. He kept us informed though. The flight itself was smooth. I would definitely fly with Allegiant again!

I had a fantastic experience with Allegiant. I had wheelchair assistance and they helped me find my luggage and brought me to my car. Even loaded my luggage. Wonderful service!! Thank you Allegiant!

Superb. Staff great. Great flight. As with other airlines, seating too tight and restrictive.

There is not one likable thing about this airline. It’s starts with the deceptive pricing and continues through the whole flight. The worst staff I’ve ever experienced way over priced bags absolutely no food or drink (unacceptable and you should be embarrassed) the seats are cramped and uncomfortable there is no entertainment there is nothing about this trash airline that constitutes any amount of money. It’s worse than spirit and way more expensive it is disgraceful. Do not travel with Allegiant I repeat do not bother no matter what they say the price is it is never ever going to be the right choice I’m mind blown at how awful the entire experience was I’m embarrassed that I chose so poorly I cannot reiterate enough how beyond horrible this company and its staff are, not one person on this flight or at the airport is qualified to sweep up trash on a city sidewalk they should certainly never be given any job that requires a brain or manners or communication with human beings, what a disgrace to the human race. Your criminal chiselers and should be put out to pasture

Great flight. Friendly staff. Free snacks and drinks would be nice. I would love fewer taxes and fees added on.

My 90 year old father flew with me. He needed wheel chair assistance and is nearly deaf. The staff was amazing with him.

It was fine. Nobody was outstandingly friendly but no one was rude and everything was smooth . The captain thanked us for flying but no one greeted me as I walked on the plane or as I exited which is the least they could do lol

Clean, friendly, roomy. But check-in from the phone link was terrible. Repeated attempts wouldn’t save at the final step. Just kept spinning! It was very frustrating. Finally, I used the app (vs website link) to check-in which worked very smoothly on the first attempt.

The new planes (American Eagle) are beautiful and especially comfortable. The flight attendants are consistently professional and courteous. And, while it may seem inconsequential, the new liquid tube of coffee creamer—in contrast to the powdered coffee creamer—makes all the difference in a cup of coffee.

Boarding was quick and efficient. We arrived at our destination early.

I'm not sure American is capable of on-time arrivals and departures. When you land at ORD, you almost always get held on the tarmac because your gate is still occupied. I may have missed my connection, but that ended up up being significantly delayed as well. Once again, I finally got home well after midnight.

Crew at the gate was very crabby and not at all polite. The plane was very hot the entire flight. And the seat cushion was very worn out.

The staff are very, very professional. It's what flying should feel like.

Flight was delayed half hour before boarding, but when I checked flight aware the plane that would Pick us up had a delay of more than an hour. AA should let us know in advance to avoid waiting several hours in the airport

Delays with no explanation. It could have been handled better.

Jill was the flight attendant in first class she was fabulous!! Best flight attendant I have had in years.!! And I fly every other week. Other can learn from her!!

As a first class customer, there was no power the entire flight which limited my ability to work. I find this unacceptable. The first 11 rows on the left side of the plan were out. I was only offered the option to charge my phone which was not the issue because my laptop was out of power. I asked if there was anything that can be done for me, and the answer was, "no". I was not offered any type of compensation for this AA problem which caused me unnecessary stress due to inability to address business issues on an already challenging travel day. Flight attendants tried to reset the power once but that was the extent of their support. Very disappointing for the lack of expected services on a flight. Please contact me with customer focused response to this complaint.

There was no inflight service. Once we landed we were delayed to find a gate for an hour and a half which was 1/2 the total time in the air.

They switched our terminal 3 times and we were delayed for four plus hours!!!

It was an early flight and most people napped/slept and the crew let us which was nice.

The crew acted like they had never done this and kept barking passive aggressive orders at people. + the security line + the delay + sitting on the tarmac for 2 hours + none of the apps or signage updating with correct times

More inflight connection. And leg space is horrible. And the paying for baggage I'd ridiculous!!!

My flight was originally from SAT to MCO connecting from MCO to ORD. We got diverted to ATL and than Frontier staff there was sooo un helpful first they said they couldn’t give us any accommodation since our flight first got delayed that cancelled and now it’s 221am and I am still in ATL since they said they need to create a new flight my final destination is ORD and I have been delayed twice and cancelled. With no real help the frontier app didn’t work no email updates over all such a horrible experience

There's no seats that lean back with little leg space i wad uncomfortable the entire flight. Your charges for extra baggage is despicable and costly!!

There was no food and no entertainment, so I'm not sure why these are even in the survey, as my understanding is frontier does not ever offer food without a few, not even a snack, and there are no screens so unless the flight safety talk is our entertainment why ask how we liked it?. One of the flight attendants say in the back of the plane as people filed in to their seats, yelling orders about where to put baggage and telling people to hurry up. It was the least professional experience I've ever had on a flight.

Good for a budget airline! It was easy to get on, staff was really nice. Can’t say anything about the food or entertainment because it wasn’t available, which is fine.

This company socks. It's fraud. They canceled our flight yesterday, and today we were late because of a really long line at the check in bag. At the rebook station, there was ton of people. The workers were all rude. I am gonna make a report to FTC.

Not clean and was told I would get a great seat and it was not great at all

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.