The Chicago Marathon, known officially as the Bank of America Chicago Marathon, began with its inaugural race in 1977. This first marathon attracted approximately 4,200 runners to the streets of Chicago, highlighting the city's growing interest in long-distance running and fitness events. The race started in Grant Park, which served as the venue for the finish line as well, allowing spectators to cheer on participants as they completed the course. The route took runners through several Chicago neighborhoods, including Lincoln Park, Lakeview, and the Near West Side, providing a picturesque view of the city's skyline while emphasizing the spirit of community engagement.

Among the starters were both elite runners and amateurs, which set a tone of competitiveness mixed with the joy of participation. Organizers aimed to promote health and fitness by encouraging citizens to engage in running and athletic activities. This inclusion of both serious athletes and recreational runners helped to cultivate an atmosphere that celebrated personal achievement as much as competitive success. The marathon's inception marked a significant moment in Chicago's sporting culture, laying the groundwork for annual events that would encourage physical fitness.

The event quickly grew in popularity, leading to the establishment of a marathon tradition in Chicago. Over the years, the race expanded to accommodate thousands of runners, and it became an iconic event on the city's calendar, attracting international participants and attention. By creating a platform for runners from all walks of life to come together, the Chicago Marathon fostered a sense of unity and community through sport, which resonated with local and visiting spectators alike.