Auburn Boulevard is a major thoroughfare in Sacramento County, California, United States, and a tiny portion in Placer County, California carrying surface street traffic through the local communities of North Sacramento, Arden-Arcade, Foothill Farms, Citrus Heights, and Roseville. It was formerly part of U.S. Route 40, a former cross-country highway connecting downtown Sacramento to Roseville and points beyond. To a lesser extent, most of Auburn Boulevard was also part of U.S. Route 99E, an eastern branch of the former U.S. Route 99, now succeeded by State Route 99.