What airlines fly to Illinois?

United Airlines, American Airlines and Frontier are the top three most popular airlines that fly to Illinois from Colorado according to our data. United Airlines is the first choice among our users, with 33% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 5 different airlines that fly to Illinois on a routine basis, so you have a few additional options to choose from.

How many flights depart from Colorado to Illinois on average per day?

As of December 2025, 80 flights take off from Colorado and land in Illinois each day. The most common flight departure time for this route is 12:00PM, with 49% of daily flights taking off in the afternoon.

How long is the flight from Colorado to Illinois?

The flight from Colorado to Illinois depends on which airports you’re departing and arriving from and whether or not you have a layover. If you fly from Denver (a popular airport in Colorado) to Chicago O'Hare Intl Airport (the most popular airport in Illinois), then the flight time is 2h 23m on average. If you fly from Colorado Springs (another popular airport in Colorado) to Chicago O'Hare Intl Airport, then the average flight time is 2h 34m.

How many flights depart from Colorado to Illinois on average per week?

The number of flights available between Colorado and Illinois is 560 per week as of December 2025. The most frequent departure day is Mon, with 17% of weekly flights leaving on this day.

What is the cheapest airline that flies from Colorado to Illinois?

Southwest, United Airlines, and Delta are the most popular carriers operating from Colorado to Illinois

When did momondo last update prices for flights from Colorado to Illinois?

Prices for flights from Colorado to Illinois are updated daily.

How many operators does momondo search for flights from Colorado to Illinois?

As of December 2025, there are 5 operators available to choose from for flights from Colorado to Illinois.

How old do you have to be to fly from Colorado to Illinois?

The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Colorado to Illinois.

What documentation or ID do you need to fly to Illinois?

The required travel and health documents for your Illinois trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Illinois. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

$28 Cheap Flights from Colorado to Illinois in 2025/26

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Find the cheapest flights from Colorado to Illinois

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One-way

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Cheap round-trip flights

Enter your travel dates to find the best prices.

10:43 am - 2:05 pm

DEN

MDW

2h 22mnonstop

3:00 pm - 4:49 pm

MDW

DEN

2h 49mnonstop

$96Frontier

Fri, Jan 9 - Mon, Jan 12

7:26 pm - 10:56 pm

DEN

ORD

2h 30mnonstop

7:50 pm - 9:49 pm

ORD

DEN

2h 59mnonstop

$97Frontier

Fri, Jan 9 - Mon, Jan 12

8:30 am - 2:54 pm

COS

ORD

29h 24m1 stop

2:13 pm - 9:55 am

ORD

COS

20h 42m1 stop

$189Multiple Airlines

Thu, Feb 26 - Sun, Mar 1

1:38 pm - 9:15 pm

DRO

ORD

6h 37m1 stop

7:00 am - 11:05 am

ORD

DRO

5h 05m1 stop

$200United Airlines

Fri, Jan 16 - Mon, Jan 19

5:30 pm - 8:47 pm

DEN

PIA

2h 17mnonstop

8:35 am - 10:20 am

PIA

DEN

2h 45mnonstop

$209United Airlines

Wed, Jan 14 - Wed, Jan 21

12:08 pm - 3:57 pm

COS

ORD

2h 49mnonstop

11:50 am - 1:54 pm

ORD

COS

3h 04mnonstop

$225American Airlines

Sat, Jan 17 - Sun, Jan 18

3:07 pm - 10:38 pm

COS

ORD

54h 31m2 stops

4:43 pm - 9:40 am

ORD

COS

17h 57m1 stop

$228Multiple Airlines

Sun, Jan 18 - Sun, Jan 25

12:17 pm - 6:22 pm

DEN

PIA

5h 05m1 stop

5:06 pm - 10:36 pm

PIA

DEN

6h 30m1 stop

$229American Airlines

Thu, Feb 19 - Mon, Feb 23

3:50 pm - 11:10 pm

MTJ

MDW

6h 20m1 stop

7:55 am - 3:10 pm

MDW

MTJ

8h 15m2 stops

$304Southwest

Thu, Feb 12 - Mon, Feb 16

3:50 pm - 12:20 am

MTJ

MDW

7h 30m2 stops

5:15 am - 3:10 pm

MDW

MTJ

10h 55m2 stops

$359Southwest

Thu, Feb 12 - Mon, Feb 16

Frontier flights from Colorado to Illinois

Our best Frontier deals on Colorado to Illinois flight tickets

Frontier

Jan 9

DEN10:43 amDenver Intl

2h 22m

MDW2:05 pmChicago Midway

Jan 12

MDW3:00 pmChicago Midway

2h 49m

DEN4:49 pmDenver Intl

$96

Find similar

Frontier

Jan 9

DEN7:26 pmDenver Intl

2h 30m

ORD10:56 pmChicago O'Hare Intl

Jan 12

ORD7:50 pmChicago O'Hare Intl

2h 59m

DEN9:49 pmDenver Intl

$97

Find similar

Frontier

Jan 28

DEN5:11 pmDenver Intl

26h 55m

1 stop

STL9:06 pmLambert-St Louis

Feb 2

STL1:40 pmLambert-St Louis

2h 36m

DEN3:16 pmDenver Intl

$104

Find similar

United Airlines flights from Colorado to Illinois

Our best United Airlines deals on Colorado to Illinois flight tickets

United Airlines

Dec 31

DEN6:00 amDenver Intl

2h 44m

ORD9:44 amChicago O'Hare Intl

Jan 1

ORD8:45 amChicago O'Hare Intl

2h 50m

DEN10:35 amDenver Intl

$157

Find similar

United Airlines

Dec 31

DEN6:00 amDenver Intl

2h 44m

ORD9:44 amChicago O'Hare Intl

Jan 10

ORD12:53 pmChicago O'Hare Intl

2h 58m

DEN2:51 pmDenver Intl

$176

Find similar

United Airlines

Jan 16

DRO1:38 pmDurango La Plata County

6h 37m

1 stop

ORD9:15 pmChicago O'Hare Intl

Jan 19

ORD7:00 amChicago O'Hare Intl

5h 05m

1 stop

DRO11:05 amDurango La Plata County

$200

Find similar

Fly from

Fly to

Route

Depart

Return

Price

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Fri 1/9

10:43 am-2:05 pm

Nonstop2h 22m

Chicago Midway

Mon 1/12

3:00 pm-4:49 pm

Nonstop2h 49m

$96

DenverChicago

DEN - ORD

DENORD

Denver Intl

Fri 1/9

7:26 pm-10:56 pm

Nonstop2h 30m

Chicago O'Hare Intl

Mon 1/12

7:50 pm-9:49 pm

Nonstop2h 59m

$97

Colorado SpringsChicago

COS - ORD

COSORD

Colorado Springs

Thu 2/26

8:30 am-2:54 pm

1 stop29h 24m

Chicago O'Hare Intl

Sun 3/1

2:13 pm-9:55 am

1 stop20h 42m

$189

DurangoChicago

DRO - ORD

DROORD

Durango La Plata County

Fri 1/16

1:38 pm-9:15 pm

1 stop6h 37m

Chicago O'Hare Intl

Mon 1/19

7:00 am-11:05 am

1 stop5h 05m

$200

DenverPeoria

DEN - PIA

DENPIA

Denver Intl

Wed 1/14

5:30 pm-8:47 pm

Nonstop2h 17m

Greater Peoria

Wed 1/21

8:35 am-10:20 am

Nonstop2h 45m

$209

Colorado SpringsChicago

COS - ORD

COSORD

Colorado Springs

Sat 1/17

12:08 pm-3:57 pm

Nonstop2h 49m

Chicago O'Hare Intl

Sun 1/18

11:50 am-1:54 pm

Nonstop3h 04m

$225

Colorado SpringsChicago

COS - ORD

COSORD

Colorado Springs

Sun 1/18

3:07 pm-10:38 pm

2 stops54h 31m

Chicago O'Hare Intl

Sun 1/25

4:43 pm-9:40 am

1 stop17h 57m

$228

DenverPeoria

DEN - PIA

DENPIA

Denver Intl

Thu 2/19

12:17 pm-6:22 pm

1 stop5h 05m

Greater Peoria

Mon 2/23

5:06 pm-10:36 pm

1 stop6h 30m

$229

MontroseChicago

MTJ - MDW

MTJMDW

Montrose County

Thu 2/12

3:50 pm-11:10 pm

1 stop6h 20m

Chicago Midway

Mon 2/16

7:55 am-3:10 pm

2 stops8h 15m

$304

MontroseChicago

MTJ - MDW

MTJMDW

Montrose County

Thu 2/12

3:50 pm-12:20 am

2 stops7h 30m

Chicago Midway

Mon 2/16

5:15 am-3:10 pm

2 stops10h 55m

$359

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first

How to get the cheapest flight ticket from Colorado to Illinois

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

Prices

Airlines

Other information

What is the cheapest month to fly to Illinois?

The cheapest month to fly to Illinois from Colorado is in January. Flight prices, which tend to average around $179, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of January, then flying in February is also cheap. Prices for this month can be found on momondo for an average of $185.

What is the cheapest day to depart on your flight to Illinois?

The cheapest day to depart from Colorado to Illinois is on a Thursday when prices can be found for as low as $301. Flights from Colorado to Illinois on a Sunday will generally be more expensive and average around $518. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

What is the cheapest time of day to depart on your flight to Illinois?

Our most recent data shows that the best time of day to fly to Illinois is in the evening. Flights from Colorado to Illinois during this time can be as low as $199. Flights at noon are often more expensive with an average ticket price of $621.

What is the cheapest Colorado to Illinois flight route?

Fly from Denver Intl to Chicago O'Hare Intl for the best Colorado - Illinois flight prices

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

You are more likely to see cheaper flights to Illinois from Colorado when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $242 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from Colorado for as low as $201 on momondo.

What cabin class options are available on Colorado to Illinois flights?

There are 4 cabin classes available to choose from on Colorado to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Colorado to Illinois flights?

No. A direct flight is the cheapest option for a flight between Colorado to Illinois.

Cheap Colorado to Illinois flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Colorado to Illinois

Best Price Found	$124
Fastest flight time	1h 56m
Direct flights	Every day
Airports in Illinois	98 airports

The best one-way flight to Illinois from Colorado in the past 72 hours is $124. The best round-trip flight deal from Colorado to Illinois found on momondo in the last 72 hours is $180.

The fastest flight from Colorado to Illinois takes 1h 56m

Direct flights go from Colorado to Illinois every day.

There are 98 airports in Illinois. From Colorado there are direct flights to Greater Peoria (PIA), Lambert-St Louis (STL), Moline Quad-City (MLI).

Search flight deals

When did momondo last update prices for flights from Colorado to Illinois?
Prices for flights from Colorado to Illinois are updated daily.
How many operators does momondo search for flights from Colorado to Illinois?
As of December 2025, there are 5 operators available to choose from for flights from Colorado to Illinois.
How old do you have to be to fly from Colorado to Illinois?
The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Colorado to Illinois.
What documentation or ID do you need to fly to Illinois?
The required travel and health documents for your Illinois trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Illinois. We recommend that you seek guidance from your airline or a reliable third party such as IATA.
What is the most popular plane model from Colorado to Illinois?
Based on momondo bookings for this flight route, the most popular plane model on flight routes from Colorado to Illinois is Airbus A321neo (16.14% of total bookings). The next most popular plane models are Boeing 737-800 (10.18%), Boeing 757-300 (9.32%), and Boeing 737-900 (9.18%).

Best airlines flying from Colorado to Illinois

Compare and see reviews for airlines that fly from Colorado to Illinois with momondo

Airline	Rating	Free Cancellation	Price
Frontier	PriceFrom $64	Free Cancellation	Rating 5.8 3,078 reviews	Search Frontier flights
Allegiant Air	PriceFrom $77	Free Cancellation	Rating 7.2 701 reviews	Search Allegiant Air flights
Southwest	PriceFrom $156	Free Cancellation	Rating 8.0 4,254 reviews	Search Southwest flights
American Airlines	PriceFrom $156	Free Cancellation	Rating 7.2 11,051 reviews	Search American Airlines flights
United Airlines	PriceFrom $162	Free Cancellation	Rating 7.4 9,102 reviews	Search United Airlines flights

Why use momondo?

Why should I use momondo to find a flight deal from Colorado to Illinois?

momondo compares prices from hundreds of airlines and agents so you can find and book the best deal on flights from Colorado to Illinois. Millions of users trust and use momondo every year so you are in good hands.

Can I find flights from Colorado to Illinois with flexible booking policies on momondo?

Flights from Colorado to Illinois with flexible booking policies can be found by using the search form above and then selecting our dedicated flexible booking filter, which will highlight only the flights where this policy is applied.

How can momondo help me find flights from Colorado to Illinois?

Once you have performed a search in the form on the page, momondo provides useful filters and insights. We can show you the cheapest days and times to fly as well as help filter your options to help you make an informed choice when booking flights to Illinois from Colorado.

I’m not ready to book a flight from Colorado to Illinois right now. Can momondo alert me if prices change?

If you are not ready to book a flight from Colorado to Illinois now, use our insights above to find helpful tips or alternatively set up a price alert, where momondo will track prices on flights to Illinois and let you know when they change.

An easier way to manage your Illinois trip

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Find better results for your trip to Illinois

Popular cities in Illinois

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Cheap flights from Colorado to Illinois from $28

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Colorado to Illinois departing on 1/10. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.

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Big names and deals

Filter for what you want

Filter for what you want

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Find the cheapest flights from Colorado to Illinois

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Frontier flights from Colorado to Illinois

Our best Frontier deals on Colorado to Illinois flight tickets

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Use the filters below to find and compare flights from Colorado to Illinois that are best for you.

See travel insights to Illinois from

How to get the cheapest flight ticket from Colorado to Illinois

What is the cheapest month to fly to Illinois?

What is the cheapest day to depart on your flight to Illinois?

What is the cheapest time of day to depart on your flight to Illinois?

Our most recent data shows that the best time of day to fly to Illinois is in the evening. Flights from Colorado to Illinois during this time can be as low as $199. Flights at noon are often more expensive with an average ticket price of $621.

What is the cheapest Colorado to Illinois flight route?

Fly from Denver Intl to Chicago O'Hare Intl for the best Colorado - Illinois flight prices

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

What cabin class options are available on Colorado to Illinois flights?

There are 4 cabin classes available to choose from on Colorado to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Colorado to Illinois flights?

No. A direct flight is the cheapest option for a flight between Colorado to Illinois.

What is the cheapest airline that flies from Colorado to Illinois?

Southwest, United Airlines, and Delta are the most popular carriers operating from Colorado to Illinois

What airlines fly to Illinois?

How many flights depart from Colorado to Illinois on average per day?

As of December 2025, 80 flights take off from Colorado and land in Illinois each day. The most common flight departure time for this route is 12:00PM, with 49% of daily flights taking off in the afternoon.

How many flights depart from Colorado to Illinois on average per week?

The number of flights available between Colorado and Illinois is 560 per week as of December 2025. The most frequent departure day is Mon, with 17% of weekly flights leaving on this day.

How long is the flight from Colorado to Illinois?

Cheap Colorado to Illinois flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Colorado to Illinois

Best Price Found

Fastest flight time

Direct flights

Airports in Illinois

When did momondo last update prices for flights from Colorado to Illinois?

How many operators does momondo search for flights from Colorado to Illinois?

How old do you have to be to fly from Colorado to Illinois?

What documentation or ID do you need to fly to Illinois?

What is the most popular plane model from Colorado to Illinois?

Best airlines flying from Colorado to Illinois

Compare and see reviews for airlines that fly from Colorado to Illinois with momondo

Why use momondo?

Why should I use momondo to find a flight deal from Colorado to Illinois?

Can I find flights from Colorado to Illinois with flexible booking policies on momondo?

How can momondo help me find flights from Colorado to Illinois?

I’m not ready to book a flight from Colorado to Illinois right now. Can momondo alert me if prices change?

An easier way to manage your Illinois trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.

Get notified when prices go down

Daily price changes in your inbox - only with Price Alerts.

Find better results for your trip to Illinois

Popular cities in Illinois

Popular flights according to clicks in the last 7 days on momondo