The 2 1/2-hour parade begins at 12:30 p.m. at Jefferson and Powell streets, and streets in the area will be closed starting at 8 a.m., according to the San Francisco Municipal Transportation Agency.
The event celebrates the culture of Italian Americans and is the longest continuously-run Italian heritage parade in the U.S., organizers said. The first took place in 1868 in San Francisco's downtown and Sunday's event is the 153rd parade.
The route winds south through North Beach on Columbus Avenue and ends in Washington Square in front of Saints Peter and Paul Church. Viewing is available along the entire route.
City transportation officials urge participants to take public transit, taxis, bike or walk to the event. Riders taking BART should transfer at Embarcadero Station and take an F Market train or a bus to Fisherman's Wharf.