I'll go with history and say a big precedent in naming was the "United Netherlands," which would have been one of the few examples of a republic in 1776. I'd make the assumption that the historical name carried on. read more
So the United States is united, but not unitary. Something united does not need to be uniform. In fact, if it were uniform it would no longer be united, it would be unitary. read more
The United States of America (USA), commonly known as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major self-governing territories, and various possessions. read more