Quote from : Made in America: An Informal History of the English Language in the United States Book

Considerable thought was given in early Congresses to the possibility of renaming the country. From the start, many people recognized that United States of America was unsatisfactory. For one thing, it allowed of no convenient adjectival form. A citizen would have to be either a United Statesian or some other such clumsy locution, or an American, thereby arrogating to ourselves a title that belonged equally to the inhabitants of some three dozen other nations on two continents. Several alternatives to America were actively considered -Columbia, Appalachia, Alleghania, Freedonia or Fredonia (whose denizens would be called Freeds or Fredes)- but none mustered sufficient support to displace the existing name.