Mountain Pass is an unincorporated community in San Bernardino County, California, United States. It is situated on Interstate 15 in the southeast mountainous desert region of the state approximately 15 miles from the Nevada border at an elevation of 4,730 feet —the highest point along I-15 between California and Nevada. It has a population of 30.The most prominent feature of the town, and its reason for existence, is the Mountain Pass Mine, an open pit mine for rare-earth elements.