Cal. Gov. Code § 23102
The boundaries of Alpine County are as follows:
Beginning at the north corner, at a point where the state line crosses the east summit of the Sierra Nevada Mountains, being the most easterly corner of El Dorado; thence southwesterly along said summit to a point two miles west of James Green's house, in Hope Valley, called Thompson's Peak; thence southwesterly in a direct line to a point on the Amador and Nevada turnpike road in front of Z. Kirkwood's house, being the common corner of Amador, Alpine, and El Dorado; thence south across the north fork of the Mokelumne River to the road leading from West Point, in Calaveras, to Big Tree road, near the Big Meadows; thence easterly along said West Point road to the Big Tree road; thence easterly in a direct line to where the Sonora trail strikes the middle fork of the Stanislaus River; thence easterly along said trail to the summit of the Sierra Nevada Mountains; thence northerly along said summit to the dividing ridge between the West Walker and Carson Rivers; thence northeasterly along said dividing ridge to the state line, forming the easterly corner of Alpine and northerly corner of Mono; thence northwest along said state line to the place of beginning.
Ca. Gov. Code § 23102