According to the U.S. Census Bureau, ZIP Code Tabulation Areas (ZCTAs) are generalized representations of U.S. Postal Service ZIP Codes. Currently, each ZCTA is built by aggregating Census 2010 blocks, whose addresses use a 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. For more information, see https://www.census.gov/programs-surveys/geography/guidance/geo-areas/zctas.html.