I do not know why geneologist, including professionals maintain this convention. Folkes! The United States, as such, are not even a dream much prior to 1776. This is why you have a Continental Congress prior to the Constitution. The exact date at which the former British Colonies of America become the United States of America is even in debate. Some, probably the majority, date it to the Declaration of Independence, others contend the adoption by Congress of the Constitution, others not until it is ratified by the states in 1789. I am sorry, my ancestors came to a specific colony in America. I simply use the colony name, i.e., Massachusetts Colony, Georgia Colony, until dates posted after Jul 1776. Just makes sense.