Hilmar (formerly, Hillmar) is an unincorporated community in Merced County, California. It is located 4.25 miles (6.8 km) west-southwest of Delhi, at an elevation of 92 feet (28 m). For census purposes, Hilmar is aggregated with nearby communities into the census-designated place Hilmar-Irwin, California. Hilmar began as a colony of Swedish immigrants in 1917. The first post office opened in 1920. It is the home of the Hilmar Cheese Company.