Information on the GNIS is available at the United States Board on Geographis Names website.
Information on the geographic names data product is available at the USGS The National Map Geographic Names website.
Geographic Names contain the same names data that USGS has been publishing on its maps for years, and the metadata was updated in 2013. The GNIS query form is available at the GNIS web site. The only way to identify the source (or bibliographic citation...