Shamrock Shuffle kicks off early Sunday in Grant Park

CHICAGO (WLS) -- Chicago's spring running season gets underway Sunday with the 37th annual Bank of America Shamrock Shuffle.

An estimated 25,000 people are expected to participate in what is known as the world's largest 8K race.

The run starts at 8:30 a.m. The route begins and ends in Grant Park.

However, police will start enforcing "No Parking" zones along the course starting at 6 a.m.

Some roads in Grant Park closed Saturday. Other roads on the route will shut down at 8 a.m.