You may have been misinformed, or maybe not. At all events, according to
this page at Wikipedia, Franklin is the most common name for a town in the United States and all of its territories and dependencies--but that is only in 26 such states. No town name is listed for all fifty states.
It has long been a commonly accepted but false chestnut that the name Springfield occurs in every state. However, the linked Wikipedia page shows that to be teh case in one 17 states.