Elk Grove is a Locality in Sacramento County, California, located just south of the state capital of Sacramento. It is part of the Sacramento–Arden-Arcade–Roseville Metropolitan Statistical Area. As of the 2010 census, the population of the city is 143,885. The second-largest city in Sacramento County, Elk Grove earned the title of the fastest growing city in the U.S between July 1, 2004 and July 1, 2005.