Mt Tam was a sacred place to the Coast Miwok people for thousands of years before the arrival of Europeans and Americans. By the late 19th century, San Franciscans were escaping the bustle of the city with all-day outings on the mountain, and in 1896 the ‘world’s crookedest railroad’ (281 turns) was completed from Mill Valley to the summit. Though the railroad was closed in 1930, Old Railroad Grade is today one of Mt Tam’s most popular and scenic hiking and cycling paths.

Mt Tam's first preserved park areas were by the Marin Municipal Water District in 1917.