Slide 24 of 29
Notes:
To be able to provide statistical data by ZIP Codes, the Census Bureau has created the ZIP Code Tabulation Area or ZCTA to be as close an approximation to actual ZIP Code coverage as possible but also having the characteristics of other statistical areas, such as definable boundaries. The Census Bureau uses the addresses in its Topologically Integrated Geographic Encoding and Referencing System or TIGER database and Master Address File database to determine the areas covered by each ZIP Code and uses that information to interpolate boundaries for these areas as they relate to Census 2000 blocks. This means that the Census Bureau will create Zip Code Tabulation Areas by grouping whole census blocks. The ZIP Code used by the majority of addresses in a given block will determine the ZIP Code Tabulation Area code for that block. While there is no legal or operational requirement for the Postal Service to abide by these boundaries the Census Bureau believes that ZIP Code Tabulation Areas will closely follow actual ZIP Code coverage. Also note that P.O. Boxes and rural routes will not have accompanying ZIP Code Tabulation Areas.
