The first recorded crossing of Pedro Mountain was by the Portola expedition in October 1769. The Spanish explorers described it as "a very bad road up over a high mountain" that, while manageable on the ascent, had "a very hard abrupt descent on the opposite side." Their route, now called the Indian Trail, ran from Martini Creek over Saddle Pass and down into what is today the Linda Mar district of Pacifica. For the next eight decades, this basic routing served as the only way over the mountain. After the Mexican-American War, the path was known as Road Trail, running east-west along the ridge from Saddle Pass and descending above Adobe Drive toward the Sanchez Adobe. Even on horseback, it was considered barely passable.

From 1879 to 1914, the Half Moon Bay-Colma Road attempted to solve the problem by routing closer to the ocean on steep switchbacks. The solution was marginally better. Charlie Nye Jr., a longtime coastside resident, recalled the experience decades later: "The road coming over Pedro Mountain was terrible, just awful. Words can't describe it. It went around turns and more turns, hairpin turns, short turns, backward turns. There were potholes on top of potholes." The Ocean Shore Railroad, operating from 1907 to 1920, provided an alternative, but after the railroad's bankruptcy, travelers were stuck with the mountain again. In 1915, a new paved route called Coastside Boulevard offered genuine improvement, climbing from Higgins Road in Pacifica back toward Saddle Pass. This routing survived until 1937, when Highway 1 was finally rerouted along Devil's Slide. Cyclists now unofficially call the remnants of the old road "Planet of the Apes."

Pedro Mountain Road's crumbling pavement can still be found between Montara and Pacifica. In some places the roadbed has washed out; in others, landslides have partially buried it. A short stub of the original highway remains in use in Montara near a local nursery. But the old routes are accessible to hikers, mountain bikers, and horseback riders, and walking them offers a visceral understanding of why the road was so feared. The route begins at a chain-link fence in Montara and climbs to an elevation of 930 feet before descending into Pacifica as Higgins Way. Near the top, it intersects with the North Peak Access Road leading to Montara Mountain's summit. Where drivers once white-knuckled their way around blind curves, hikers now pause to admire views that no one traveling the old road at eight miles per hour ever had the composure to enjoy.