In addition to Kentucky, Massachusetts, Pennsylvania, and Virginia, the United States has two other commonwealths, Puerto Rico and the Northern Mariana Islands, but they are of a different kind. They are not states, and have only a nonvoting representative in Congress.

The term "Commonwealth" can be confusing because it refers to two different things. In the United States, there are four states that officially call themselves Commonwealths: Kentucky, Massachusetts, Pennsylvania, and Virginia. This title is purely ceremonial and reflects their historical transition from British rule to self-governing representative democracies; legally, they are identical to the other 46 states. If you are looking for the "Commonwealth of Nations" (formerly the British Commonwealth), there are currently 56 member countries, including major "states" (nations) like Canada, Australia, India, South Africa, and the UK. Some people mistakenly refer to the 7 Original Members of the modern Commonwealth: Australia, Canada, India, New Zealand, Pakistan, South Africa, and the United Kingdom. Additionally, the U.S. has two "Commonwealth" territories—Puerto Rico and the Northern Mariana Islands—which are self-governing but under U.S. sovereignty. Always clarify if you are discussing U.S. domestic geography or global geopolitics when using this term.