The largest rare earth element mine in the United States is the Mountain Pass mine, which is situated in San Bernardino County in the state of California, specifically within the Mojave Desert region near the California-Nevada border. This prominent mining facility holds strategic national importance because it represents the primary domestic source for rare earth elements, which are critical components utilized in a wide array of advanced technology applications, including electric vehicle motors, wind turbines, consumer electronics, and various defense systems. The deposit at Mountain Pass was originally discovered back in the mid-twentieth century, and after experiencing various periods of active production, ownership transitions, and environmental modernizations, the facility has scaled up its operations significantly to re-establish a secure and reliable domestic supply chain. Operating the mine involves extracting bastnäsite ore, which is subsequently processed to separate individual rare earth elements. While the raw extraction occurs at this desert location, geopolitical and supply chain dynamics have historically influenced how the extracted concentrates are processed globally, though recent decades have seen extensive investments aimed at ensuring full domestic processing capabilities within American borders to reduce reliance on foreign entities.