Chicago Marathon, Oct 11, 2026
How CTA buses ran on Marathon Sunday
The Marathon closed 26 miles of streets on Oct 11. CTA kept 97% of its usual buses running on the 34 routes it rerouted, and where buses still came, waits were normal. But the reroutes left hundreds of stops near the course without their usual buses for hours. We compared every bus, every 30 seconds, with the two Sundays before.
Bus stops near the course, 10 minutes a frame. Red: in a gap of 90 minutes or more between its usual buses. Amber: where the runners were, from the race plan. The count is citywide, so it includes a few dozen stops beyond this map, almost all on #8 Halsted. Search for a stop below the map to see its day.
Look up your route
Buses mostly stuck to CTA's posted reroutes. Pick a route to see its reroute and when its cut-off stops got buses back.
Almost no buses crossed the course all morning
Between 7 and 11:30 AM, one bus crossed the course at street level, against about 2,300 on a normal Sunday. To get across, buses went under it on I-55 and I-290.
Most trips ran on reroutes
73% of the trips on the 34 routes scheduled between 6:30 AM and 6 PM ran on reroutes (2 to 3% on a normal Sunday). Reroutes skip stops, so the number of buses held up while visits to the regular stops fell 24%.
470 stops got none of their buses from 7:30 AM to 3 PM
On the two Sundays before, it was 0 and 19. Where buses still came, people waited about as long as usual.
Waits for someone arriving at a random time, at the 2,874 stops (2,968 stop-and-route pairs) that had a bus every hour on all three Sundays. Near State & Madison at 12:40 PM, 90 of 91 stops were in a gap of 90 minutes or more.
When buses came back
Half of the cut-off stops had a bus again by 5:53 PM. On all 18 busy course streets, the first bus came after the city's planned reopening time, a median of about 2½ hours after. Bus data can't say why: police reopen the streets, and when they did isn't published.
City's plan: streets close, then reopen behind the last runners
Reopening street by street from 10:30 AM, the finish area last at 6 PM
CTA's race-day alerts
Bus Tracker showed detours
Cut-off stops: when half had missed a bus, and when half had one again
What this data can't show
- CTA's shuttles to Navy Pier and the Museum Campus never appeared in Bus Tracker. Their stops, and those of #22's Clark St shuttle, are left out of the counts (52 in all).
- Bus Tracker lost track of more buses than usual: 8.9% of bus time on the 34 routes from 7 AM to 6 PM, against 3.3 to 4.3% normally.
How we measured this
- Data
- Every CTA bus every 30 seconds from Bus Tracker, with CTA's detour records and alerts. Normal Sundays: Sep 27 and Oct 4, same schedule. Buses out and visits are counted 6:30 AM to 6 PM.
- Bus visits
- A bus's GPS track passes within 40 meters of the stop. This is stricter than our live map, which uses CTA's distance along the route: that was wrong for detoured buses.
- Gap
- 90 minutes or more between a stop's usual buses, where both normal Sundays had at least 3.
- Cut off
- No bus of the route from 10 AM to noon, where both normal Sundays had 2 or more.
- Sources
- Ridership: City of Chicago data portal. Course: © OpenStreetMap contributors (ODbL). Runner positions: the organizers' plan. Code.