Zzyzx, formerly Soda Springs, is an unincorporated community in San Bernardino County, California, United States, within the boundaries of the Mojave National Preserve, managed by the National Park Service (NPS), an agency of the U.S. Department of Interior, as public land. It is the former site of the Zzyzx Mineral Springs and Health Spa and now the site of the Desert Studies Center. The site is also the location of Lake Tuendae, originally part of the spa, and now a refuge habitat of the endangered Mohave tui chub.

Route 15, consisting of the contiguous segments of State Route 15 (SR 15) and Interstate 15 (I-15), is a major north–south state highway and Interstate Highway in the U.S. state of California, connecting San Bernardino, Riverside, and San Diego Counties. The route consists of the southernmost 289.24 miles (465.49 km) of I-15, which extends north through Nevada, Arizona, Utah, Idaho, and Montana to the Canada–US border. It is a major thoroughfare for traffic between San Diego and the Inland Empire, as well as between Southern California, Las Vegas, Nevada, and the Intermountain West.