Greenfield is a census-designated place in Kern County, California. It is located 7mi south of Bakersfield, at an elevation of 351 feet . The population was 3,991 at the 2010 census.The Delkern post office was opened in 1949. That name derives from Kern Delta, a designation for the surrounding area.DemographicsThe 2010 United States Census reported that Greenfield had a population of 3,991. The population density was 2,681.4 people per square mile (1,035.3/km²). The racial makeup of Greenfield was 2,512 (62.9%) White, 71 (1.8%) African American, 63 (1.6%) Native American, 45 (1.1%) Asian, 1 (0.0%) Pacific Islander, 1,112 (27.9%) from other races, and 187 (4.7%) from two or more races. Hispanic or Latino of any race were 2,263 persons (56.7%).The Census reported that 3,991 people (100% of the population) lived in households, 0 (0%) lived in non-institutionalized group quarters, and 0 (0%) were institutionalized.There were 1,244 households, out of which 522 (42.0%) had children under the age of 18 living in them, 709 (57.0%) were opposite-sex married couples living together, 149 (12.0%) had a female householder with no husband present, 106 (8.5%) had a male householder with no wife present. There were 74 (5.9%) unmarried opposite-sex partnerships, and 6 (0.5%) same-sex married couples or partnerships. 225 households (18.1%) were made up of individuals and 97 (7.8%) had someone living alone who was 65 years of age or older. The average household size was 3.21. There were 964 families (77.5% of all households); the average family size was 3.63.