This Sunday morning, the San Francisco Marathon returns for its 42nd edition. Nearly 26,000 runners and more than 80,000 spectators are expected to fill the city on race day.

Five different races will take participants to the Embarcadero, Marina, North Beach and over the Golden Gate Bridge. From there, they'll head into the Presidio, the Richmond, Golden Gate Park, the Upper and Lower Haight, the Mission, Potrero Hill, Dogpatch, and Mission Bay.

There's even a chance to run two marathons; starting at midnight, some will follow the marathon course in reverse, with a brief detour along the Great Highway, before joining others for the second loop.

As a result, locals can expect significant traffic and transit delays across the city on Sunday.

The marathon course route. | Image: Via SF Marathon

The official marathon will start at 5:30 a.m. at Mission Street and the Embarcadero, while the first half marathon kicks off there at 6:30 a.m. At 6:45 a.m., the second half-marathon will start in Golden Gate Park; back at Mission Street and the Embarcadero, the 5K race will start at 7:45 a.m.

While some reserved parking will be available, organizers say that parking in the city will be a challenge, especially with all the traffic shutdowns.

BART won't be running early enough for marathon runners to get to the starting line on time, but buses will transport participants from the Walnut Creek, El Cerrito Plaza, MacArthur, Bay Fair, Daly City, and Millbrae BART stations, arriving by 4:45 a.m. to the Embarcadero.

Locals can also arrive by bike, with a bike valet station operating at Market Street and the Embarcadero from 4:30 a.m. to 1 p.m. Bikeshare, e-scooters and carpooling are also options for getting to the race.

After the race, BART will be running normally; attendees are advised to purchase their return tickets in advance to avoid lines.

Shuttles will also be available for attendees of both half-marathons, running from Golden Gate Park to the Embarcadero.

Road closures across the city on race day. | Via: SF Marathon

Roads will begin closing along the marathon route at midnight on Sunday, gradually reopening along the route between 10 a.m. and 2:45 p.m.

Drivers are discouraged from using their cars during the marathon hours, but the Golden Gate Bridge will nonetheless remain open for vehicle traffic in both directions throughout the event.

The east side bridge sidewalk will open at 8:45 a.m. to bikes and pedestrians, while the west side bridge sidewalk will open at 10 a.m. to bikes only. The Vista Point parking lot will be closed from 4 a.m. to 5 p.m. Some cross-traffic will be allowed along the route, as runner flow permits.

As a result of the road closures, many Muni lines will be impacted during the event. Riders should expect reroutes and delays across the city.

Road closures around the start and finish line. | VIA: SF MARATHON

As for spectators, they can stay connected with friends and family members running the marathon by following them on an interactive online map.

For more details and updates, head over to the SFMTA's and the SF Marathon's websites.