Altamont Pass

Altamont Pass, formerly Livermore Pass, is a low mountain pass in the Diablo Range of Northern California between Livermore in the Livermore Valley and Tracy in the San Joaquin Valley. The name is actually applied to two distinct but nearby crossings of the range. The lower of the two, at an elevation of 741 ft, carries two railroad rights-of-way and Altamont Pass Road, part of the old Lincoln Highway and the original alignment of US 50 before it was bypassed c. 1937. The bypass route travels over the higher summit, at 1,009 ft, and now carries Interstate 580, a major regional highway heavily congested by Central Valley suburbanization.

Of the two railroad lines through the old pass, one is still in use: the ex-Western Pacific line built in 1908 over the pass, which is sometimes known as the Altamont Corridor, now owned by Union Pacific.

Source: Wikipedia