At 10,064 feet, Mount San Antonio (known by locals as Mt. Baldy) is the highest point in Los Angeles County and an iconic figure in the L.A. skyline, looming above the city with its magnificent snow-capped peaks. The upper south face of Mount San Antonio is formed by a fluvial cirque (Baldy Bowl), which is an amphitheater-like valley formed by glacial erosion. Baldy Bowl features the San Antonio Ski Hut, built in 1937 by the Sierra Club, and the hut still serves as a site for picnics and day-use activities. This bowl led to the local moniker for the mountain as well.
Mount San Antonio is the highest peak in the San Gabriel Mountains and was formed as a result of a transform fault in the San Andreas Fault system. The name Mount San Antonio is largely attributed to Antonio Maria Lugo, a rancho owner in the 1840s. It is believed he named the mountain in honor of Saint Anthony of Padua. Prior to this, the mountain was called Avii Kwatiinyam by the Mohave people and Yoát or Joat by the Gabrielino-Tongva tribe, whose history in the Los Angeles basin dates back 7,000 years ago.
The earliest white settlers in the area were Mormons who settled at Lytle Creek Canyon in 1851. In the late 1870s and throughout the 1880s the area was mined for gold, and remnants of the Hocumac Mine and the Gold Ridge Diggings can be seen today. Both mines were unsuccessful due to uncertain water supply and a low yield of gold in the ore. In 1921, the Mt. Baldy Schoolhouse was opened and today this structure serves as the Mt. Baldy Visitor Center.
During Prohibition, Camp Baldy was developed into a getaway resort with a casino, swimming pool, and dance pavilion by Foster Curry, Ruth Curry, and film star Edmund Burns. These structures were largely destroyed by a flood in 1938.
The Devil's Backbone Trail was developed by the Civilian Conservation Corps in 1935-1936, leading from Mt. Baldy Notch to the summit.