The United States Geological Survey Geographic Names Information System is a database of more than 2,000,000 place names within the United States. It is one place to search for a location when online interfaces to modern maps fail.
There is more about this database on their site. There is a link to the search page there as well.
If you have a place name you cannot find on the USGS n and you have an idea of where it might be, try searching digital images of old newspapers for the place name. It may be mentioned in old newspaper articles even though it’s not an “official” place.