Atwater is a city on State Route 99 in Merced County, California, United States. Atwater is 8 miles (13 km) west-northwest of Merced, at an elevation of 151 feet (46 m). The population as of the 2010 census was 28,168.
According to the United States Census Bureau, the city has a total area of 6.1 square miles (16 km2). 99.86% of it is land and 0.14% water.
The city includes Castle Air Museum, but does not include Castle Air Force Base proper.
The railroad reached Atwater in the 1870s, and a town grew up. The first post office opened in 1880. Atwater incorporated in 1922. The name honors Marshall D. Atwater, a wheat farmer whose land was used by the railroad for its station.
North of the town is Castle Air Force Base the former World War Merced Army Airfield.
On May 15, 2020, Atwater declared itself a business ‘sanctuary city’ during the coronavirus pandemic.
At the 2010 census Atwater had a population of 28,168.