Lincoln Acres is an unincorporated community of San Diego County located wholly within the boundaries of the incorporated city of National City. It has a population of approximately 2,100 residents, and residents may keep livestock. Lincoln Acres has a fire station and library. The community relies on the San Diego County Sheriff's Office to provide …Lincoln Acres is an unincorporated community of San Diego County located wholly within the boundaries of the incorporated city of National City. It has a population of approximately 2,100 residents, and residents may keep livestock. Lincoln Acres has a fire station and library. The community relies on the San Diego County Sheriff's Office to provide police protection. Sheriff Deputies from the Imperial Beach station police the neighborhood. The United States Postal Service once listed the zip code 91947 as being located within Lincoln Acres for P.O. Box use, however the post office has since closed and residents receive mail under the zip code 91950. The community is in area code 619.