Santa Clarita is a city in northwestern Los Angeles County in the U.S. state of California. With a 2020 census population of 228,673, it is the third-most populous city in Los Angeles County, the 17th-most populous in California, and the 103rd-most populous city in the United States. It is located about 30 miles (48 km) northwest of downtown Los Angeles, and occupies 70.75 square miles (183.2 km2) of land in the Santa Clarita Valley, along the Santa Clara River. It is a classic example of a U.S. edge city, satellite city, or boomburb.

Interstate 5 (I-5) is a major north–south route of the Interstate Highway System in the United States, stretching from the Mexican border at the San Ysidro crossing to the Canadian border near Blaine, Washington. The segment of I-5 in California runs 796.77 miles (1,282.28 km) across the length of the state from San Ysidro to the Oregon state line south of the Medford-Ashland metropolitan area. It is the longest interstate in California, and accounts for more than half of I-5's total length.