Columbia Gazetteer of the World
Online version of this standard reference work on geographic place names and features.  Some earlier editions also in print, Main Library and Armstrong Reference G103 .L7
Geographic Names Information System (GNIS)
The Geographic Names Information System (GNIS), developed by the USGS in cooperation with the US Board on Geographic Names (BGN), contains information for almost 2 million physical and cultural geographic features in the United States and its territories.