California, Vermont, Texas, Hawaii
While this question asks for four, it should be noted there were other republics that joined the Union:
Republic of West Florida (Approx 3 months before the US annexed it.)
Republic of South Carolina (Existed for almost two months before the formation of the Confederacy) (But, for the sake of the question, they were previously part of the union. You could count, if you want to, the first time S.C. declared itself a republic. On 3/26/1776, they declared their independence from Great Britain, more than 3 months before the U.S. Declaration of Independence. Whether it was recognized or not is a different matter. That being said, the California Republic was not recognized by any nation either and lasted less than a month.)
They were independent republics
Commonwealth of Independent States
Nations that had been colonies of Britain withdrew from the British Commonwealth to form independent republics. This included the United States, as well as several countries in Africa.
They need to sustain the trade flow established during Soviet times
it means to kill Bryan
They were independent republics
Texas was in independent republic before statehood.
Commonwealth of Independent States
Vermont was briefly an independent republic before joining the newly-formed United States in 1791.
That would be the Commonwealth of Independent States, CIS.
Some of the Greek city-states were republics, Athens for example.
The Commonwealth of Independent States also known as the CIS was formerly known as The Russian Commonwealth. The organization was regional and was formed after the breakup of the former Soviet Union and its participating countries were former Soviet Republics.
Yes, they are. All six of the former Yugoslav republics (Slovenia, Croatia, Bosnia, Montenegro, Serbia and FYR Macedonia) are recognized as independent states. The secessionist (former Serbian autonomous province of) Kosovo also declared independence. It is recognized by 76 out of 193 UN member states. Serbia disagrees and considers Kosovo to be its rebel province.
Nations that had been colonies of Britain withdrew from the British Commonwealth to form independent republics. This included the United States, as well as several countries in Africa.
They need to sustain the trade flow established during Soviet times
it means to kill Bryan
CIS stands for the Commonwealth of Independent States, a regional organization made up of former Soviet republics. The CIS countries are former Soviet republics that have chosen to cooperate on issues such as trade, security, and cultural exchange.