If you want to know where US flights run late, start at the hubs — because hub delays ripple outward across the whole network. Using full-year 2024 US DOT Bureau of Transportation Statistics (BTS) on-time data, the major hubs we track ranked clearly: Dallas–Fort Worth (DFW) was the weakest on punctuality and cancellations, while Los Angeles (LAX) and Atlanta (ATL) ran best.
These are real BTS arrival/departure and cancellation figures for the latest complete reporting year (2024); see our methodology for exactly how they are computed.
Which hub airports had the worst delays in 2024?
Here are the five major hubs we track, ranked from worst to best on-time departure rate, with full-year 2024 BTS figures:
| Airport | On-time departure % | On-time arrival % | Avg delay, delayed flights (min) | Cancelled % |
|---|---|---|---|---|
| DFW — Dallas–Fort Worth | 71% | 74% | 74.2 | 1.86% |
| DEN — Denver | 76% | 80% | 62.5 | 1.13% |
| ORD — Chicago O’Hare | 77% | 78% | 76.4 | 1.35% |
| ATL — Atlanta | 79% | 82% | 60.7 | 1.00% |
| LAX — Los Angeles | 81% | 80% | 70.1 | 0.81% |
Source: US DOT BTS, Airline On-Time Performance, full-year 2024. See each hub’s full profile: DFW, DEN, ORD, ATL, LAX.
A few things stand out. DFW is worst on both the on-time bar and cancellations — a busy American Airlines fortress hub exposed to Texas convective weather. ORD has the longest average delay of the group (about 76 minutes among delayed flights), so when O’Hare is late, it is very late. And LAX, despite heavy congestion, cancels the fewest flights, partly because its mild coastal weather rarely forces wholesale cancellations.
Why are these the worst-performing hubs?
Hub delays almost always trace back to a mix of three forces:
- Weather. Chicago and Denver are the textbook weather-prone hubs — snow and ice in winter, thunderstorms in summer. DFW adds violent spring and summer convective storms.
- Volume and congestion. ATL, ORD and DFW each handle on the order of a thousand-plus departures a day. When demand brushes against runway capacity, small disruptions queue up.
- Late-arriving aircraft. The single largest network-wide delay cause. One late inbound jet delays its next several flights, so morning slips snowball into afternoon chaos — we cover this in US flight delay causes explained.
This is why the “average delay among delayed flights” column matters as much as the on-time rate. DEN and ATL clear delays faster (60–62 minutes); ORD’s delayed flights sit nearly 16 minutes longer on average.
Worst months to fly through each hub
Delay risk is seasonal, and the worst month differs by hub:
| Airport | Worst month | Best month | Leading delay cause |
|---|---|---|---|
| DFW | June | October | Late-arriving aircraft, convective weather |
| DEN | December | September | Weather (snow and convective) |
| ORD | January | October | Weather, late-arriving aircraft |
| ATL | July | November | Late aircraft, summer storms |
| LAX | December | September | Volume, late-arriving aircraft |
If your trip is flexible, the best month column is the cheapest insurance you can buy.
What this means for your trip
- Connecting through DFW, ORD or DEN in their worst months? Pad your layover. Our connection buffer guide suggests at least 60–90 minutes for a domestic connection below roughly 75% on-time.
- Booking a route anchored at a strong hub like ATL or LAX usually means better reliability — compare the routes themselves on our route on-time pages.
- Read on-time and cancellation rates together. A hub can post a decent on-time number while cancelling more flights; see what ‘on-time’ really means for why the 15-minute rule hides this.
The bottom line
In full-year 2024 BTS data, DFW was the worst major hub for delays and cancellations, ORD had the longest delays, and LAX and ATL were the most dependable of the group. These are estimates of reliability drawn from the public record — always confirm a specific carrier and date against the live BTS source before you book a tight itinerary.