$27 Find Cheap Flights from Colorado to Illinois

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1 adult, Economy, 0 bags

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Low seasonJanuary
Cheapest flight$27
Best time to beat the crowds with an average 6% 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 (245 flights per week), American Airlines (123 flights per week), and Air Canada (120 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 92% 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 $238.

  • 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 $294. On the other hand, the most expensive day to fly is Sunday, where round-trip prices are $528 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 $128 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 $128.

  • 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 42% 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 708 direct flights each week.

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

    There are around 137 direct flights from within Colorado to Illinois every day. Most flights (58%) depart in the morning.

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

    Each week there are around 958 direct flights from within Colorado to Illinois. The most common day for departures is Sunday, with 17% of flights taking off on this day.

  • How long is the flight to Illinois?

    An average nonstop flight from Colorado to Illinois takes 6h 29m, covering a distance of 927 miles. The shortest route is Denver (DEN) to St. Louis (STL) with an average flight time of 2h 00m.

  • 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 958 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 (14%) and Peoria (3%). Searches for flights to Moline (2%), to Bloomington (1%) 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 4280 reviews
8.1Boarding
8.0Comfort
7.5Entertainment
8.6Crew
7.0Food
Airline reviews

The seats are now more narrow. I paid for front row the seats in the front are even more narrow than before.

2.0 MediocreDavid, Feb 2026
SAN - LAS
Read more Southwest reviews

The seats are now more narrow. I paid for front row the seats in the front are even more narrow than before.

Only downside was the legroom and seat width, which is always a problem unless I spend more for a premium seat.

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

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

Very bad! They kept delaying my flight and wouldn’t do anything about it

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

The boarding process needs to be fixed. The zone don't work, especially when there is hardly anyone in zones 3, 4,and 5, leaving the majority of the passengers backed up in the aisle, especially because passengers seated near the front are blocking passengers who are seated in the rear of the plane. It would also help if the size of carry on bags was more strictly enforced.

Awful. They won’t help me with anything. I booked on American but they abdicated to Iberia. The ticket was overpriced. Everything negative

I enjoyed the extra leg room compared to other airlines. The first stewards made my daughter’s birthday special by giving her an extra snack. Then the last one coming home from Chicago to Appleton made our night really enjoyable Thanks for making our trip enjoyable

It was good..clean, comfy seat. Friendly warm welcoming crew. Was able to check my cabin luggage at the gate which I was able to pickup in a decent time from baggage claim. The app gave all updates from delays to baggage claim info. Overall smooth flight.

It was a typical flight. We had a delay which seems to be the normality now. And we had no in flight service due to conditions.

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.

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.

Very well recently! Frontier is improving and less harrassing customer on luggages! Positive!

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.

I am writing to express my disappointment with my recent Frontier Airlines flight. I was charged $99 at the gate because my bag was said to be too large, yet once onboard there was no available overhead bin space, and I was required to place the bag under the seat in front of me anyway. This made the charge feel unnecessary and unfair. Additionally, before the flight even took off, I was asked to move from the seat I paid for into a middle seat so another passenger and her cat could have my seat to themselves. I was not offered compensation or an explanation for being moved from a paid seat. Between the unexpected bag fee and being forced to give up my seat, this experience fell well below acceptable customer service standards. I would appreciate a review of this situation and appropriate compensation.

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

Too many extra fees, uncomfortable, little leg room. Will not recommend this airline.

Frontier is the Walmart of airlines. Frontier has removed adjustability and comfort from their seats to make the flight lighter and save gas. This makes it impossible to sleep on their flights. Their customer service is abysmal. Once, I bought a drink on the plane, and they swiped my credit card on the plane to pay for it. Then I got three weeks of daily notices from my bank telling me they tried to charge the wrong card number over and over again. I tried to call them, but they removed the ability to actually talk to someone that can resolve such a problem from their company to cut corners. The only way to talk to someone in person is to go to the check-in counter at the airport (40 minutes drive from my house). Eventually their system gave up on trying to charge the card, after 21 days of repeated tries. They don't pad their prices even a little to handle customer service issues like missed flights. They also have a blanket policy preventing helping you reschedule a missed flight if their system says you "cancelled" your own flight online. This is a major problem because their website is broken on mobile devices, the only web browser you have at the airport when their gate staff tell you that you have to reschedule your own missed flight online because they can't help you. I tried to reschedule my flight on my android device and instead, their website crashed and "cancelled" my missed flight. When I got to the counter, the agent argued with me for 5 minutes insisting that I intentionally cancelled my own flight (implying I had to buy another flight). She missed the point: the problem was that I could not buy another flight because their website is broken. I left to avoid more conflict with the "customer service" agent. I tried to redress my issue with their only other "customer service" chanel available: the contact form on their website. The response I got was more of the same: you cancelled your own flight, according to our website / computer records, therefore we won't help you. I was trying to explain the problem with their broken website that cost me hundreds of dollars by crashing / malfunctioning and resulting in a cancelled flight, but they only had deaf ears for this problem. Worst customer service I have ever experienced. I will never buy another Frontier flight again, because it is a risky, painful move that I will likely regret often.

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.