Mountain Pass, California is a small–unincorporated community located in San Bernardino County, California fifteen miles southwest of Primm. With an elevation of over 4,700 feet, Mountain Pass is the highest point on Interstate 15 in California. Despite being in the Mojave Desert, its elevation causes it to receive more precipitation than the low lying areas and it supports more plant life. Creosote scrub and Joshua trees grow in the area.
Mountain Pass has a cooler climate than the surrounding desert valleys. Average high temperatures in the summer are near 90 degrees with low temperatures in the 60s. Daytime highs in the winter are typically in the 50s with lows slightly below freezing. Mountain Pass averages eight inches of precipitation per year, three inches more than Primm. In the winter, the area receives occasional snowfall, with an average amount of nine inches per year.
There is a rare earth metals mine in Mountain Pass that has now been shut down. It has deposits of bastnäsite, from which the following can be extracted: Cerium, Neodymium, Europium, and Lanthanum. Europium is used for the red light in cathode ray tube ("CRT") screens. The mine is now mostly inactive due to environmental concerns. Due to the increasing demand for these rare earth metals, the mine resumed full operations in 2013. However, in 2015 the company that owns the mine declared bankruptcy and the mine closed again.
Mountain Pass sits at the southern edge of the Clark Mountain Range. The range extends for about fifteen miles in a southwest–northeasterly direction. Its tallest peak, Clark Mountain, at 7,933 feet, is five miles northwest of Mountain Pass. Pinyon pines, juniper, and rare white fir trees grow at the higher elevations.
Clark Mountain is also a world–class rock climbing area. Its exposed limestone rock attracts climbers from all over.