St. Louis to Chicago

What the Data Says About STL to ORD

The St. Louis to Chicago corridor (STL → ORD) covers roughly 258 miles and is served by 37 carriers, based on Bureau of Transportation Statistics reporting. Across 13,549 flights in the dataset, this route posts a 80.8% on-time rate with an average delay of 99.1 minutes when flights run late. Over the most recent 24 months of BTS data, 5,544 flights were recorded on this pairing — 88 cancelled (1.6%) and 3 diverted (0.1%). Those baseline metrics tell you what to expect before you book.

Having 37 carriers on the route matters: more carriers generally means more daily schedule options, competitive pricing, and redundancy when flights are cancelled. With 13,549 total flights analyzed, the 80.8% on-time figure is statistically meaningful rather than a small-sample fluke. The 99.1-minute average delay applies only to flights that actually ran late, so it is not the average wait across all departures — the majority of flights on this route depart on time under the BTS definition of a delay (15+ minutes past schedule).

Looking at recent months, Mar 2024 posted the best performance on this corridor at 85% on-time, while Jul 2025 came in at 62% on-time — a 23-point gap between best and worst recent month. For travelers evaluating the STL to ORD route, the combination of a 80.8% on-time rate, 99.1-minute average delay, 1.6% recent cancellation rate, and 37 available carriers is the concrete summary of what BTS data shows about reliability on this pairing.