Rosemead is a city in Los Angeles County, California, United States. The 2020 United States Census reported a population of 51,185. Rosemead is part of a cluster of cities, along with Alhambra, Arcadia, Temple City, Monterey Park, San Marino, and San Gabriel, in the west San Gabriel Valley with a growing Asian-American population.

State Route 19 is a state highway in the U.S. state of California, running along Lakewood Boulevard and Rosemead Boulevard in the Los Angeles area. An additional "hidden" state highway, State Route 164, is also signed as part of SR 19, despite having a legal description separate from Route 19. The combined route is a north–south four-to-six lane suburban roadway, lying east of the Long Beach Freeway and west of the San Gabriel River Freeway, and connecting the eastern parts of Long Beach and Pasadena via the Whittier Narrows. Under their legal descriptions, SR 19 runs north to Gallatin Road in Pico Rivera, then SR 164 goes from Gallatin Road to Pasadena. Since 1998, several pieces have been relinquished to local governments, and more transfers are authorized by state law.