Forget the mayor’s race. Forget ballot measures about crime and schools. For many San Franciscans, short of the presidency, the most important contest on Tuesday will determine the future of one short road.

It is not just any road. It is a quintessential California stretch — so magnificent, it is named the Great Highway — that hugs the city’s westernmost edge, offering sweeping views of pelicans swooping over the Pacific Ocean and of surfers tackling its mighty waves.

Proposition K on the San Francisco ballot would permanently close the flat, two-mile stretch of pavement to cars. The measure would turn it over to cyclists, pedestrians, roller skaters and dogs, charting a path, backers promise, to create the city’s next great park. Think the High Line or Hudson River Yards in New York City, they say.

But in San Francisco, where small ideas regularly lead to huge fights, the squabbles over the road’s fate have become louder than sea gulls at a beach picnic.

“It feels like people on all sides are fighting for their lives,” said Marjan Philhour, who is running for the city’s board of supervisors to represent the Richmond District, the neighborhood just north of Golden Gate Park.