This site makes extensive use of the geographic feature names and locations as maintained by the U.S. Geological Survey (USGS) in the USGS Geographic Names Information System (GNIS), the official Federal database for domestic geographic feature names data as designated by the U.S. Board on Geographic Names.
The U.S. Board on Geographic Names serves the Federal Government and the public as a central authority to which name problems, name inquiries, name changes, and new name proposals may be directed. In partnership with Federal, State, and local agencies, the Board provides a conduit through which uniform geographic name usage is applied and current names data is promulgated. Note that the identifying attributes for named physical and cultural featuress (GNIS Feature ID, Official Feature Name, and Official Feature Location) are American National Standards Institute standards as specified in ANSI INCITS 446-2008.
Also note that while the HomeTownLocator gazetteers list all features by their official names, some unofficial alternative or historical names for populated places can also be used for name searches. For example, New York City was named "New Amsterdam" when the town was first incorporated in 1653 as part of a Dutch colonial settlement. A more recent unofficial alternative name for New York City is "The Big Apple". A search for either "New Amsterdam" or "Big Apple" (quotes are not necessary) in the New York Gazetteer will lead you to the community profile for New York City.
The city/ZIP Code associations, coordinates for ZIP Code centroids and the classification of city names as "Preferred", "Acceptable Alternative" or "Not Acceptable" are updated quarterly from a commercial distribution of the US Postal Service database.
The most definitive data is Census 2000 information and it is identified as such where used. The site also includes the most recent estimates produced by the US Census Bureau. The latest data released on July 1, 2010 are estimates for July 1, 2009.