Thirty years after its inception, the great race across Chicago would be almost unrecognizable to the first contestants. The number of people participating swelled tenfold, from 4,000 to 40,000. Women made up almost half the field of the Chicago Marathon, a far cry from the handful in the early years. And what was once an amateur event, loosely organized and with no cash prize, has become a $650,000 competition run by people trying to gain every edge, from formulated sports drinks to lightweight, breathable fabrics.

On this day, September 25, in 1977, the Chicago Marathon, called the Mayor Daley Marathon in honor of the late city mayor, was first held.

The 1977 marathon was the first one of the modern era, but hardly the first one to run in Chicago. The city was just the second to start an annual tradition of Marathon runs: Boston began theirs in 1897 and the First Chicago Marathon ran on Saturday, September 23, 1905. The race began in Evanston and finished, with less than half of the original field, at Washington Park race track, greeted by a standing-room-only crowd.