Latitude Maps

How can I find a County,State given a Latitude and Longitude?

I am writing a C# program to find the County ,state and 10 nearest cities for a given Point(Latitude ,Longitude).How can I know the given latitude and longitude is in one county and state.

Public Comments

1. each point corresponding to a latitude and longitude can only belong to one county in one state
2. Go to U.S.G.S. web site and do some research, buy a globe, buy an atlas, try HARDER
3. If you download Google Earth, that is is pretty convenient way to surf around and find lat longs easily.