BUFFALO, N.Y. -- A popular race returns to Buffalo's Delaware Park Thursday evening: the J.P Morgan Corporate Challenge.

The 3.5-mile race is part of the world's largest corporate road racing series. Organizers say it attracts around 12,500 participants from 359 Buffalo companies. The race starts at Delaware Park on Amherst Street just west of Colvin at 6:45 p.m.

Streets that will be closed while the race is going on include Amherst from Colvin to Delaware, Delaware from Amherst to W. Ferry, and Nottingham and Middlesex, between Delaware and Amherst.