More than 55,000 runners will start the Chicago Marathon on a fast course. The route is a 26.2-mile loop through 29 neighborhoods, crossing the Chicago River six times. The course is flat until the final half-mile, where runners face a small climb.

Starting at Grant Park, runners head north along the lakefront, then west and south through various neighborhoods. The course includes several aid stations with water, lemon-lime Gatorade, and medical tents. GPS watches may be unreliable due to signal interference. Read more culture coverage.

The route passes through diverse neighborhoods, including Northalsted and Pilsen, with various cheer zones and cultural performances. Runners will find Maurten gel stations and refill stations along the way. The final stretch includes timing mats and a final climb up 'Mount Roosevelt'. Related: Jepkosgei Sets New Record at Cardiff Half Marathon.

This original Runner World brief is based on reporting from Marathon Handbook. Visit the source for its complete reporting, context and any later corrections.