Pardon me, but I took that from your "about page." As a practical matter, what's the difference between a state and a commonwealth?
http://ask.yahoo.com/20001117.html
...'A search on "state difference commonwealth" turned up some useful results. At the About.com: Lawyers site, we learned that there are four commonwealths in the United States: Massachusetts, Pennsylvania, Virginia, Kentucky.
The difference between these commonwealths and the other 46 states is in name alone -- they elected to call themselves commonwealths, a term drawn from political theory. The About.com lawyer assured us that, legally, there is no difference between a state and these four commonwealths.
http://www.answerbag.com/q_view.php/8310
According to the website of the Secretary of the Commonwealth of Massachusetts: At the time of the American Revolution, "commonwealth" was a popular term for describing a state/nation where the people came together by mutual consent. It was a term with democratic overtones, in contrast to the monarchic system that the colonies were trying to throw off. John Adams put the word "commonwealth" into his 1780 draft of the Massachusetts Constitution and it was accepted, as opposed to earlier rejected versions that used the term "state". So that's why Massachusetts is a commonwealth. Given that Virginia and Pennsylvania would have written their Constitutions around the same time, a similar idea might have factored in for them. Kentucky came later, so it's anyone's guess, but it's still one of the older states... it seems possible that the same idea could apply.