Chicago Marathon

Of the Majors, yes, and not by a little. The whole course sits within 8 m of vertical range, from 176 m to 184 m; Berlin, the flat course everyone names, has 21 m. Of the 28 courses compared it's third. Amsterdam and the Gold Coast are each flatter by half a metre or less, and neither is a Major. The ground under Chicago is a lake plain, so the only relief on the course comes from bridges and expressway underpasses.

USGS NED 10 m lidar, sampled every 25 m, smoothed over 100 m. Raw-to-smoothed ratio 1.39.

Sound for height, about 4 % out for distance. The published reference file carries only 163 points, one every 0.3 km, which is too sparse to sample elevation against, so it was map-matched onto the street network first. The matched line runs 43.8 km against a certified 42.195. The heights hold and so does the flatness, but treat the kilometre marks on this page as approximate.

Our own measurement, against the certified distance.

Seven times, more than anywhere but Berlin. Steve Jones in 1984, Khalid Khannouchi in 1999, Catherine Ndereba in 2001 and Paula Radcliffe in 2002. Then Brigid Kosgei in 2019, Kelvin Kiptum with 2:00:35 in 2023 and Ruth Chepngetich with 2:09:56 in 2024. Kiptum's stood until Sabastian Sawe ran under two hours at London in 2026; Chepngetich's is still the women's world record. She was banned for three years in 2025 after a positive test dated March 2025. The ruling left earlier performances official, so the record stands, and the integrity unit says its wider investigation continues.

World Athletics record progression and Athletics Integrity Unit rulings, checked September 2026.

Roughly one in four on the usual arithmetic, and that's generous. The 55,000 places it divides into include charity, time-qualifier, legacy and tour-operator entries that never go near the drawing, so the true lottery rate is worse than one in four. New York accepted about one per cent in 2026, and London's latest ballot took 1.34 million applications. Third-party estimates for Berlin run from one in five to one in three, and Sydney's draw came out at roughly one in three.

Third-party reporting; the organiser publishes no acceptance rate.

Hot enough to have stopped the race once. The 2007 edition was halted mid-course at 31 °C. A runner died that day; the medical examiner put it down to a heart condition, not the heat. The median temperature during the race window is 14.4 °C, but treat that series with care. It samples the second Sunday in October every year, and Chicago's race date has moved around: 2007 was run on the first Sunday and 1999 on the fourth. So the older years describe today's date, not past race days.

ERA5 reanalysis sampled on the second Sunday in October, 1995–2025. The rule does not reproduce the historical race date in every year, and the 31 °C figure for 2007 comes from the race record, not from this series.

More than 55,000 took a marathon place in 2026.

Organiser figures for the 2026 edition.

About 14.4 °C during a typical race: that's the median across 29 years, which have run from 4.4 °C to 21.4 °C. 3 of the 29 were wet.

ERA5 reanalysis for the race date, 1995-2025.

The course finishes 1 m above where it starts, so a Chicago time goes to the B.A.A. untouched. Its downhill adjustment only begins at 1,500 ft of net loss.

Net drop +1 m from this site's course line; 2027 adjustment None. Certification platinum label: World Athletics Platinum Label; record-eligible, and seven world records have been ratified on it.

It comes from USGS NED 10 m, sampled every 25 m along the course line and smoothed over 100 m. The raw-to-smoothed ratio here is 1.39. Around 1.3 means the model is reading the ground, not rooftops; above about 2.0 the total climb carries real noise, and the net change is the sturdier number.

0 missing samples · 2 bridge spans corrected.