Why Chicago is one of the fastest majors
Chicago's course runs on the city's grid, wide straight streets with almost no meaningful elevation change from start to finish. Runners lose very little to terrain, and pacing groups can hold tight, even splits for the full distance. That combination is why Chicago sits alongside Berlin as the two majors most closely associated with world-record performances, and why it is often the first choice for runners chasing a specific goal time.
The trade-off is field size. Close to 50,000 runners start each year, one of the largest fields of any major, which means a genuinely congested first mile even for well-seeded runners. Chicago rewards patience at the start as much as it rewards fitness later on.
Famous winners and defining moments
Kelvin Kiptum ran 2:00:35 here in 2023, the outright marathon world record at the time and still the men's course record. Ruth Chepngetich ran 2:09:56 in 2024, the first woman ever under 2:10 and still Chicago's women's course record. Neither is currently the outright world record (that mark moved to London in 2026), but both remain among the fastest marathons ever completed by anyone, on any course.
The most recent completed edition, October 2025, was won by Jacob Kiplimo in 2:02:23 and Hawi Feysa in 2:14:57. American Conner Mantz ran an unofficial 2:04:43 in the same race, an American record, a reminder that Chicago's flat, fast layout benefits every level of the field chasing a personal best, not only the leaders.
Chicago has also had at least one notably hot edition, in 2007, when unusually high temperatures forced organizers to halt the race for runners still on course. It is a rare exception on a course generally known for cool, favorable October weather, and worth planning for rather than assuming away.
How to train for Chicago
Chicago rewards the same kind of flat-course preparation as Berlin, with one added wrinkle: the size of the field.
Train for even, sustained goal pace
With no hills to manage, the biggest lever on your Chicago result is your ability to hold a consistent pace for the full distance. Marathon-pace tempo runs and long runs with a controlled, even effort matter more here than hill-strength work.
Build a heat-contingency plan
Most editions are cool, but Chicago has shown it can run hot. Have a simple backup plan, adjusted pace targets and a firmer hydration strategy, so an unexpectedly warm race day does not blow up your whole race.
Practice starting in a crowd
A field of nearly 50,000 means your first mile will likely be slower than goal pace regardless of your seeding. Rehearse staying relaxed and running by effort, not the clock, through a congested opening mile so you do not panic and overcorrect once the field opens up.
Course-specific pacing work on top of a real foundation is what makes a Chicago goal time realistic. Build your aerobic base and anchor the week around the long run first.
