SAN FRANCISCO -- An unusual convergence of sporting and entertainment events in San Francisco this weekend promises to bring up to a million extra people into the densely populated bayside city.

The influx could eclipse the city's own population of about 800,000.

The weekend will include the opening games of the San Francisco Giants division playoffs, a San Francisco 49ers game, the annual Fleet Week celebration featuring the Blue Angels and the America's Cup World Series yachting races.

Add to that mix a highly popular bluegrass festival in Golden Gate Park and street festivals in North Beach and elsewhere and it has the makings for jam-packed streets and transit challenges, even as the city's economy gets a boost.

James Go, 25, who works in San Francisco but lives in nearby Daly City, said he usually comes into San Francisco on weekends, but was planning to stay away this weekend.

"The population is going to double. It's not worth it," he said, as he took a break on Friday from work at a downtown office building.

City officials say they are prepared for the crowds. The city has activated its emergency operations center and the police department has limited time off and reassigned officers from administrative and investigative assignments to the street.

"We are up to this challenge," Mayor Ed Lee said at a news conference on Tuesday. "We have departments working around the clock to make sure these things are managed well."

City officials are strongly encouraging people to bike, walk or use public transportation or taxis.

The city's Municipal Transportation Agency will run extra service, particularly along the waterfront where crowds are expected to gather for Fleet Week and America's Cup events. There will also be extra taxis on the street, according to Ed Reiskin, head of the MTA.

The Bay Area Rapid Transit Agency, which runs trains through the city to other parts of the Bay area, will run longer trains.

"This is like the World Series of transportation for us," Reiskin said at Tuesday's news conference. "We're ready for it ...your job is to leave your cars at home."

Warnings are also being issued for San Francisco Bay, where endangered humpback whales have been recently spotted. The National Oceanic and Atmospheric Association wants boaters to watch for the whale's blow to avoid collisions.

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