Carrier route record

AAORD→STL

American Airlines · Chicago to St. Louis

Flights: 535
Period: July 2025 to June 2026
Share of route: 17%
Carriers: 5

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

American on ORD to STL draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 535 flights. The strongest carrier on the route with a full sample, Republic Airways, flew 444 at 76.2% on time.

Republic Airways is the most reliable of the four carriers covered here at 76.2% on time across 444 flights.

On time

65.6%

Arrivals under 15 minutes late, of 520 completed flights

Avg delay

86 min

Across delayed arrivals only, not all flights

Cancelled

2.62%

National rate is 1.81%

Whole route

71.0%

Every carrier on ORD to STL, 3,068 flights

These figures cover 535 flights between July 2025 and June 2026. Beyond the headline rate, 13.5% 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

American against every carrier on ORD to STL

American flew 535 of the 3,068 flights on ORD to STL, about 17% of it. Its 65.6% on time is 5 points worse than the route as a whole, which runs 71.0%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from Republic at 76.2% to American at 65.6%.

The choice of carrier is not cosmetic here. Republic Airways arrives on time 76.2% of the time; SkyWest Airlines manages 68.2%. Sample sizes sit next to every figure, because a two-point gap across 834 flights means less than a ten-point one.

On-time performance by carrier on ORD to STL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airways	444	76.2%	77 min	2.48%	B
Envoy Air	727	75.0%	52 min	2.34%	B
United Airlines	528	71.2%	79 min	1.33%	C
SkyWest Airlines	834	68.2%	73 min	4.20%	C−
American Airlines (this page)	535	65.6%	86 min	2.62%	C

SkyWest Airlines cancels 4.2% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

Departure window

When American runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 18 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am46 flights77.3%
11am–2pm4 flights—
2pm–5pm54 flights75.9%
5pm–8pm149 flights68.7%
8pm–5am282 flights59.8%

Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 59.8% on time, against 77.3% for the 8am–11am 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 8pm–5am window is the busiest, with 282 flights scheduled in it.

Across the year

American on ORD to STL through the year

Jul–Sep 2025186 flights61.4%
Oct–Dec 202565 flights70.8%
Jan–Mar 202646 flights52.4%
Apr–Jun 2026238 flights69.9%

Scale runs 45% to 75%. 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 65.6% on time across 535 flights.

American on ORD to STL did not run the same all year. Its best quarter was Oct–Dec 2025 at 70.8% on time and its weakest Jan–Mar 2026 at 52.4%, a swing of 18 points on roughly 134 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, Tuesday is the strongest day at 76.2% on time and Friday the weakest at 53.4%. 23 points is a smaller lever than departure hour, but it is free.

Delay causes

Why American runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 57% of the 15,000 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
57%
Carrier
34%
National Airspace System
6%
Extreme weather
3%

57% 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 15,000 reported delay minutes here, that single category outweighs weather by 20 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 15,353 reported delay minutes.

The largest share of delay minutes, 34%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 5,263 of the 15,000 delay minutes reported here.

Cancellations run at 2.62%, against 1.81% nationally. That is about one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 13.5% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

At 258 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8am–11am window matters as much as it does.

The return leg is a different operation and performs like one: it runs 80.7% on time across 533 flights, 15 points above 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 15 points of difference.

One caution: this is a thin sample. 535 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 American on ORD to STL

Put together: treat all of this as provisional. 535 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 65.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 520 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