If Daniel Boone had his way, Transylvania would have been a 14th colony and become a founding state. According to Michael J. Trinklein's Lost States: True Stories of Texlahoma, Transylvania, and Other States That Never Made It, Boone and a group of settlers claimed an area overlaying the current Kentucky, Tennessee, and Virginia, named it Transylvania, and sent a representative to Congress, but Congress wouldn't recognize its legitimacy. Virginia especially had a problem with it because it had already claimed much of the same land. Later, the undisputed bulk of Transylvania was claimed by another group that successfully got it recognized as the state of Kentucky. If Boone had been successful, Nashville could have been established in Transylvania instead of Tennessee, and as a horse breeder, Boone could have established a Transylvania Derby.
Trinklein's book also describes other altered states such as Texlahoma, the Morman state Deseret, South California, Long Island, South Jersey, West Florida, Nataqua, Half-Breed Tracts, Rough and Ready, and Lost Dakota.