Thousands of runners are expected to converge on downtown St. Louis as part of the Go! St. Louis Marathon events.
That marathon starts near the Arch and winds all the way to downtown Clayton. The starting gun fires at 7AM Saturday.
The half marathon is drawing a lot of attention this year. Organizers announced a $10,000 first prize--the fourth largest in US history for a half-marathon. The entire weekend of events could draw over 20,000 people.