The highest point on the historic U.S. Route 101 in California is Ridgewood Summit, located in Mendocino County. The pass sits at an elevation of 1,956 feet (596 meters) and serves as a natural gateway between the Ukiah Valley to the south and the Willits Valley to the north. This section of the highway crosses the Mendocino Range and marks a significant geographic divide, with the Russian River watershed on one side and the Eel River watershed on the other. Because of its altitude, Ridgewood Summit is known for experiencing much harsher weather than the surrounding coastal and valley areas, including occasional snow, thick fog, and ice during the winter months. Historically, the area was known as "Robber's Pass" in the late 19th century due to its isolation and steep terrain, making it a favorite target for stagecoach bandits like the infamous Black Bart, who famously robbed several stages near this peak.