Between Pacifica and Montara, Highway 1 used to run across a cliff that kept sliding into the Pacific. Now it runs through a mountain, and the old road is a trail.
A long fight
Starting in 1958, the state planned to replace the Devil's Slide stretch with the Martini Creek Bypass over Montara Mountain, according to Wikipedia. Community and environmental groups fought the plan for decades. A 1908 Ocean Shore Railroad tunnel in the area had been destroyed during Prohibition to keep smugglers from using it. A January 1995 slide closed the highway for five months. On Nov. 5, 1996, San Mateo County voters approved Measure T with 76% of the vote, backing a tunnel instead of the bypass.
The tunnels
Ground was broken on May 6, 2005, and the tunnels opened to traffic on March 26, 2013. They are named for the late Congressman Tom Lantos. At 4,149 feet northbound and 4,008 feet southbound, they are the second- and third-longest road tunnels in California.
The trail
San Mateo County Parks says the 1.3-mile paved trail has separate lanes for walkers and for bikes in each direction, plus overlooks with benches, observation scopes and interpretive signs. It is part of the California Coastal Trail. Parking is limited, and the county suggests taking SamTrans Route 117 on weekends.