$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 3% drop in price.
Most popular time to fly and prices are also 6% 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 (155 flights per week), American Airlines (92 flights per week), and Air Canada (74 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 90% 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 Midway Airport (MDW), with an average flight price of $225.

  • 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 $519 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 $203 on average. On average, there is no price difference when choosing to fly in the morning or the evening on this flight route. 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 $580.

  • What is the cheapest flight to Illinois?

    The cheapest ticket to Illinois from Colorado found in the last 72 hours was to Chicago O'Hare Intl Airport, at $167 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 $167.

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

    The cheapest month for flights from Colorado to Illinois is April, when tickets cost $281 (return) on average. On the other hand, the most expensive months are September and July, when the average cost of round-trip tickets is $494 and $485 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 43% 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 7 cities. The city with the most direct flights is Denver, with 456 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 (62%) 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 16% of flights taking off on this day.

  • How long is the flight to Illinois?

    An average nonstop flight from Colorado to Illinois takes 7h 09m, covering a distance of 927 miles. The shortest route is Denver (DEN) to St. Louis (STL) with an average flight time of 2h 04m.

  • 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 (84% of total searches to Illinois). The next most popular destinations are St. Louis (12%) and Peoria (2%). Searches for flights to Moline (1%), to Bloomington (0%) and to Springfield (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 4297 reviews
8.0Comfort
7.5Entertainment
8.1Boarding
7.0Food
8.6Crew
Airline reviews

I have not flown Southwest in awhile and had a very pleasant experience. From ticketing to boarding to the flight. The flight left on time and landed ahead of schedule. It won't be so long next time!!

10.0 ExcellentTy&Steph, Feb 2026
CLT - STL
Read more Southwest reviews

I have not flown Southwest in awhile and had a very pleasant experience. From ticketing to boarding to the flight. The flight left on time and landed ahead of schedule. It won't be so long next time!!

The Southwest experience has definitely taken a dive from its early days. You can no longer deferentiate from other airlines. Air travel is too expensive. Southwest is no longer budget friendly. They have lost me as a loyal customer.

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!

Excellent. Would encourage Southwest to keep current boarding procedures with free style seating. Makes for a fantastic experience

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

Crew was great (professional, attentive, prompt). Snacks for 4 hrs flight is deplorable.

United Airlines is my preferred airlines and I am thankful for Gary who also help support me on the phone to switch my flight literally last min.

Seated dude next to me even though lots of empty rows. But main thing was we sat on the tarmac after landing for 30 minutes because of, in the words of the dude who sat next to me, “operational incompetence”. We got changing directions about where to pick up gate checked bags. Pilot and flight attendant were awesome though.

It was a pretty standard flight... until the almost hour and a half spent on the taxi way. I get that the weather has been poor but the delay had nothing to do with the weather and more to do with a plane with several issues tying up the gate. I get that that happens from time to time but this has been EVERY flight I've been on for the past 5 years and I fly 3 to 5 times a year. This isn't just United... it's American, it's Delta. It's an issue with the entire industry. I work for UPS and packages on a cargo plane get better service than people do these days. Anymore I HATE flying.

Perfect flight. Smooth flight. Arrived 20 minutes early at destination. Excellent service.

The flights were on time which was great give. It was holiday travel season and there’d been some weather issues. The only complaint and this is every time with United is the terrible seat design. The head rest is not built for comfort and having my neck bent forward for a cross country trip reminded me while I try not to take United flights as a rule.

Everything was absolutely wonderful from check in to baggage claim. Staff was very professional and sweet. Will definitely recommend United to family and friends.

They did the one thing that really matters - got to Chicago early.

The flight was on time. I generally don’t drink or eat on short flights and the seats were good and the flight attendants were friendly. That’s all I expect

It was nice to have gotten up upgraded to first class with a meal on a three hour flight

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.

Check in on the web portal was cumbersome! After several attempts I finally got the boarding pass.

Excellent flight and even arrived 23 min early. No entertainment , or wi fi on board, but I downloaded a couple of movies beforehand which kept me entertained. Really like flying Allegiant airlines.

WE were delayed about an hour and never any communications from the employees working the gate. We also were moved to a total of three gates.

I love how they show love to their customers and care about them too.

The gate agent had a really bad attitude and refused to help me get on the standby list. She just handed me a card and said I needed to call a number. I asked her to help with the AA app on my phone and she just shrugged and said she didnt know. After a few phone calls, I eventually just went to a different gate agent on the other side of the terminal and got the help I needed.

Overall, my last three trips on American Airlines have all been either delayed or "rescheduled" due to mechanical issues. At least on delay caused me to miss two possible connecting flights each later than the first. My last option for my last connection required the assistance of the onsite service desk (O'Hare Airport). The wait time for the service desk was such that it jeopardized getting booked on the last connecting flight available for the night. Suffice it to say, my latest experiences with American Airlines have caused me extensive loss of productive business and personal time and can therefore be classified as significantly less than satisfactory.

Waiting for gate in RDU for more than 20mins is crazy.

American Airlines was great and worked very hard to change my ticket so I could get an earlier, direct flight back to Dallas. However, I was informed that Kayak made mistakes with my itinerary and classified my ticket as desiring to be on the earlier flight instead of taking the necessary step of calling AA to get me on the standby list. This ended up keeping me from being added to the standby list and delayed me getting home by 6 hours. I am happy to discuss this further with Kayak so they can correct their procedures so this won't happen again.

Waited for oxygen tanks for 30 minutes after boarding was complete.

We flew in first class. The crew did not offer drinks before the flight took off, but they treated us well during the flight. The food was excellent. There was actually too much food served, but it was nice to have all the options.

Update to handle the delay was very bad, crews no smiles or welcome or thanks. Don’t care attitude

Pilot navigated severe weather/snow storm with skill. Described his intentions clearly

Little warm on the plane and delayed for an hour

So excited very proud first of all I wanna thank kayak all updates very professional and fast alart And amazing cabin crew so nice to me they deserve big salute

Gate not determined until I got to the airport - hard to plan the trip to the airport.

Our flight was canceled. I will never use Kayak nor Frontier for travel again. The entire experience was a headache.

Frontier.. nickel and dime add-ons. Flight late, on time, late again, last minute gate change, arrival gate required a shuttle to the terminal. They sure keep you guessing.. if you like a little chaos and airport anxiety, this is the airline for you!

This is my second time flying with Frontier. My current experience was very favorable. The staff from the gate to the plane was friendly, warm and professional. The food options lacked in my opinion. This area needs some attention in my opinion.

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

Delayed. Text notifications were slow. Not much information o what was happening. Boarding was slow and confusing. Wasn’t even offered water other flight. Had to ask. No entertainment at all. Felt like.a Greyhound bus.

The single worst check in experience I could imagine. I’ll never do any business with Frontier or any affiliated company

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.