Chicago Spring Half Marathon 2025. The world’s largest half marathon, with 62,000 participants and 200,000 cheering spectators, awaits you! The world’s largest half marathon, with 62,000 participants and 200,000 cheering spectators, awaits you!

The world’s largest half marathon, with 62,000 participants and 200,000 cheering spectators, awaits you! 2) celebrate the 15th annual chicagoland spring marathon, half marathon & 10k!.