Geographic Names Information System

The Geographic Names Information System (GNIS) is a database of name and location information about more than two million physical and cultural features, encompassing the United States and its territories; the associated states of the Marshall Islands, Micronesia, and Palau; and Antarctica. It is a type of gazetteer. It was developed by the United States Geological Survey (USGS) in cooperation with the United States Board on Geographic Names (BGN) to promote the standardization of feature names.

Data were collected in two phases. Although a third phase was considered, which would have handled name changes where local usages differed from maps, it was never begun.

The database is part of a system that includes topographic map names and bibliographic references. The names of books and historic maps that confirm the feature or place name are cited. Variant names, alternatives to official federal names for a feature, are also recorded. Each feature receives a permanent, unique feature record identifier, sometimes called the GNIS identifier. The database never removes an entry, "except in cases of obvious duplication."

The GNIS was originally designed for four major purposes: to eliminate duplication of effort at various other levels of government that were already compiling geographic data, to provide standardized datasets of geographic data for the government and others, to index all of the names found on official U.S. government federal and state maps, and to ensure uniform geographic names for the federal government.

Phase 1 lasted from 1978 to 1981, with a precursor pilot project run over the states of Kansas and Colorado in 1976, and produced 5 databases. It excluded several classes of feature because they were better documented in non-USGS maps, including airports, the broadcasting masts for radio and television stations, civil divisions, regional and historic names, individual buildings, roads, and triangulation depot names.

The databases were initially available on paper (2 to 3 spiral-bound volumes per state), on microfiche, and on magnetic tape encoded (unless otherwise requested) in EBCDIC with 248-byte fixed-length records in 4960-byte blocks.

The feature classes for association with each name included (for examples) "locale" (a "place at which there is or was human activity" not covered by a more specific feature class), "populated place" (a "place or area with clustered or scattered buildings"), "spring" (a spring), "lava" (a lava flow, kepula, or other such feature), and "well" (a well). Mountain features would fall into "ridge", "range", or "summit" classes.

A feature class "tank" was sometimes used for lakes, which was problematic in several ways. This feature class was undocumented, and it was (in the words of a 1986 report from the Engineer Topographic Laboratories of the United States Army Corps of Engineers) "an unreasonable determination", with the likes of Cayuga Lake (in upstate New York) being labelled a "tank". The USACE report assumed that "tank" meant "reservoir", and observed that often the coordinates of "tanks" were outside of their boundaries and were "possibly at the point where a dam is thought to be".