Carrier route record

WNORD→DEN

Southwest Airlines · Chicago to Denver

Flights: 483
Period: July 2025 to June 2026
Share of route: 8%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on ORD to DEN sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 483 flights. The strongest carrier on the route with a full sample, United Airlines, flew 3,758 at 77.4% on time.

The national on-time rate over the same period is 77.6%, so Southwest on ORD to DEN runs 5 points behind the country as a whole. Across a thousand flights that is about 46 extra late arrivals.

On time

73.0%

Arrivals under 15 minutes late, of 474 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

1.66%

National rate is 1.81%

Whole route

74.2%

Every carrier on ORD to DEN, 6,169 flights

These figures cover 483 flights between July 2025 and June 2026. Beyond the headline rate, 8.9% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Southwest against every carrier on ORD to DEN

Southwest flew 483 of the 6,169 flights on ORD to DEN, about 8% of it. Its 73.0% on time is about level with the route as a whole at 74.2%. Ranked by on-time rate it is number three of five carriers on the route, where the range runs from United at 77.4% to American at 66.5%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. United Airlines arrives on time 77.4% of the time; American Airlines manages 66.5%. Sample sizes sit next to every figure, because a two-point gap across 1,471 flights means less than a ten-point one.

On-time performance by carrier on ORD to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	3,758	77.4%	73 min	0.93%	B+
Envoy Airthin sample	125	76.0%	52 min	0.00%	B+
Southwest Airlines (this page)	483	73.0%	68 min	1.66%	C
Frontier Airlinesthin sample	332	72.5%	139 min	2.11%	C
American Airlines	1,471	66.5%	76 min	1.77%	C

United leads American by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Southwest runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 36 points, against 11 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am124 flights91.9%
8am–11am18 flights—
11am–2pm105 flights80.0%
2pm–5pm61 flights66.7%
5pm–8pm175 flights55.6%
8pm–5am—

Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 55.6% on time, against 91.9% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 175 flights scheduled in it.

Across the year

Southwest on ORD to DEN through the year

Jul–Sep 2025267 flights76.4%
Oct–Dec 2025111 flights74.5%
Jan–Mar 202641 flights57.9%
Apr–Jun 202664 flights65.1%

Scale runs 50% to 80%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 73.0% on time across 483 flights.

Southwest on ORD to DEN did not run the same all year. Its best quarter was Jul–Sep 2025 at 76.4% on time and its weakest Jan–Mar 2026 at 57.9%, a swing of 19 points on roughly 121 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Wednesday is the strongest day at 82.4% on time and Friday the weakest at 62.9%. 20 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 59% of the 8,739 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Late-arriving aircraft
59%
National Airspace System
23%
Carrier
18%
Extreme weather
0%

59% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 8,739 reported delay minutes here, that single category outweighs weather by 59 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 8,739 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 91.9% on time here.

Cancellations sit at 1.66% against a national 1.81%, which is ordinary. Diversions add another 0.21%.

Connections and stage length

What a delay here costs

8.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.

The 888 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg is a different operation and performs like one: it runs 63.7% on time across 482 flights, 9 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 9 points of difference.

One caution: this is a thin sample. 483 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Southwest on ORD to DEN

Put together: treat all of this as provisional. 483 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 73.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 474 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures