erc: who: United States. Bureau of the Census. what: 1990 Census County Block Map (Recreated): Bexar County, Inset P01 when: 1990 where: https://texashistory.unt.edu/ark:/67531/metapth358717/ erc-support: who: University of North Texas Libraries what: Permanent: Stable Content: when: 20081203 where: https://texashistory.unt.edu/ark:/67531/