Throughout the United States' history, there were many different proposals that would split states to create two or more different states. These state proposals were not all approved. This map encapsulates some (probably not all) of the new state proposals, whether or not they were approved.
Idea comes from http://andrewshears.com/ but image(s) are not copyrighted material.
- The (short-lived) Conch Republic of Key West, Florida - There was talk at some point of annexing the Philippines - The Panama Canal zone could easily have become a state - Also, I read somewhere that pre-Civil War southerners were talking about annexing Cuba and dividing it into five states.