| Altamont Pass | |
|---|---|
 Wind turbines at Altamont Pass nearLivermore,California | |
| Elevation | 741 ft (226 m) |
| Traversed by | Altamont Pass Road,Union Pacific Railroad |
| Location | Alameda County, California, between theLivermore andSan Joaquin valleys |
| Range | Diablo Range |
| Coordinates | 37°44′45″N121°39′30″W / 37.74583°N 121.65833°W /37.74583; -121.65833[1] |
| Topo map | Altamont |
| New Altamont Pass | |
|---|---|
 View from westbound I-580 of Altamont Pass. | |
| Elevation | 1,009 ft (308 m) |
| Traversed by |  I-580 |
| Location | Alameda County, California, between theLivermore andSan Joaquin valleys |
| Range | Diablo Range |
| Coordinates | 37°43′9″N121°39′33″W / 37.71917°N 121.65917°W /37.71917; -121.65917[2] |
| Topo map | Altamont |
Altamont Pass, formerlyLivermore Pass, is a lowmountain pass in theDiablo Range ofNorthern California betweenLivermore in theLivermore Valley andTracy in theSan 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 (226 m), carries two railroadrights-of-way (ROWs) and Altamont Pass Road, part of the oldLincoln Highway and the original alignment ofUS 50 before it was bypassed in 1937. The bypass route travels over the higher summit, at 1,009 ft (308 m), and now carriesInterstate 580, a major regional highway heavily congested byCentral Valleysuburbanization.[3][4]
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 theAltamont Corridor, now owned byUnion Pacific. It carries freight trains as well as theAltamont Corridor Express, which gives its occasional name (ACE) and operates betweenStockton,Livermore,Pleasanton,Fremont, andSan Jose. The other and older right-of-way was the line built in 1869 with a 1,200-foot-long (370 m) summit tunnel by the originalWestern Pacific Railroad (1862–1870) as part of thetranscontinental railroad. After 1879, when asea level ferry crossing at theCarquinez Strait replaced the 1869 route, it remained in use for other purposes by theSouthern Pacific. In 1984 it was abandoned and deeded toAlameda County by Southern Pacific Railroad in favor oftrackage rights on the aforementioned ex-Western Pacific line.[5]
From 1966 to 2008, the Altamont Pass area was home to theAltamont Speedway, which became famous as the site of the 1969Altamont Free Concert, a large outdoor concert featuringThe Rolling Stones and marred by violence.[6] The pass is also known for theAltamont Pass Wind Farm, one of the largest concentrations of wind turbines in the world.[7]
From the time of theCalifornia Gold Rush, what is now Altamont Pass was called Livermore's Pass afterRobert Livermore, the owner of theRancho Las Positas and a way station near the pass. After the transcontinental railroad was built through the pass by Chinese laborers in 1869,Altamont, formerly The Summit, became a critical stopping point where helper engines pushed heavy trains over the steep grades of the pass.[8][9]
A narrow road, the Altamont Pass Road (once called the Stockton Road), was an early stagecoach route and formed part of the transcontinentalLincoln Highway. In 1938,Highway 50, a four lane freeway (now called Interstate 580) was built through Altamont Pass, replacing the two-lane Altamont Pass Road and bypassing Altamont. Four westbound lanes were later constructed in 1970.[10][4]
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