Since I've delving into my family research last year for the first time, I'd came across several American ancestors in the colonial period, whom been documented with places of birth and death ending with the "USA" or "United States" before 1776. As a constitutional/national name, the United States of America did not become official until the Second Continental Congress of 1777 adopted and finalized it for the Articles of Confederation in 15 November 1777. However, the Declaration of Independence in July of 1776 made officially an union of 13 American colonies as an united 13 states of America.

So, there was no United States of America before July 1776, only 13 British provinces (colonies) in the eastern seaboard of North America.

I think it is important to document colonial-era American ancestors having been born and died in the years before 1776, in places only identified by the colonies' provincial titles in America. You can add "USA" or "United States" to ancestors' places of birth and death in the years after July 1776.

This is just a suggestion, not a requirement. It's really up to you to do as you would like for your American ancestors. To me, it's just plain common sense to follow historic events and official, recognized titles/names of certain places.