Puerto Rico and Guam were both offered independence, and both refused although they act as independent countries in many respects. Some Native American nations today act as independent countries in some respects but not others (although each of them is independent from the individual laws of the state the nation is in). Texas was a separate country and chose to join the United States. SC, NC, FL, GA, TN, LA, AL, MS, VA, AR, TX all attempted to separate from the United States unsuccessfully.

Within the federal system some things are left to the states while others are handled by the feds. this balance has shifted over the years with states having varying degrees of independence from the federal government. Under the Articles of Confederation each state was an independent country that entered into a cooperative agreement with the other independent countries that were former British colonies in North America. this system did not work effectively and was scrapped in favor of the federal system of the Constitution.

In the end, we are a hybrid of the strong central government and a confederation of independent countries.