What is a ZCTA?
ZIP Code Tabulation Areas (ZCTAs) were developed for the 2000 Census by the US Census Bureau for tabulating summary statistics. Recognizing the fact that most people do not identify with census tracts or other census geography, the ZCTAs were created as generalized representations of US Postal Service ZIP Codes. Each ZCTA is built by aggregating Census 2000 blocks, whose addresses use a given ZIP Code, into a ZCTA which gets that ZIP Code assigned as its ZCTA code. While in most instances the ZCTA code equals the ZIP Code for an area, not all ZIP Codes have their own ZCTA. The UDS Mapper contains updated national ZCTAs reflecting U.S. Postal Service ZIP Code changes through October, 2002; there will be no further updates of ZCTA boundaries until required for the 2010 Census. See http://www.census.gov/geo/ZCTA/zcta.html for more information. In their annual preparation of Uniform Data System data from Section 330 grantees, John Snow, Inc. assures that every valid ZIP Code maps to the ZC
