F3 Half Marathon Chicago 2025 Registration. For each race, you’ll find the history of the half marathon and the course, the most recent year’s course maps,. Click above to verify your registration information.
Registration for the f3 lake half marathon & 5k will close on january 28th at noon or until we sell out. Chicago’s original winter half marathon the 13.1 mile run is long enough to check your level of endurance, but manageable enough as a barometer of your speed.