There are six commonwealths in the United States: four states — Kentucky, Massachusetts, Pennsylvania, and Virginia — and two territories, Puerto Rico and the Northern Mariana Islands. The same word covers both groups, but it does very different work in each. For the states, “commonwealth” is a historical label with no legal consequences. For the territories, it describes an actual negotiated relationship with the federal government.
The Four Commonwealth States
Kentucky, Massachusetts, Pennsylvania, and Virginia are the only states that officially use “commonwealth” in their formal names.1Mass.gov. Why is Massachusetts a Commonwealth? The word appears on their constitutions, in court documents, and on legislative headers. Virginia’s indictments still close with “against the peace and dignity of the Commonwealth,” a phrase carried forward from the state’s original 1776 constitution.2Encyclopedia Virginia. The Constitution of Virginia (1776)
Despite the distinctive title, there is no legal difference between these four and the other 46 states. The designation grants no special privileges, alters no relationship with the federal government, and changes nothing about what residents owe in taxes.3In Custodia Legis. What’s in a Name? The Four U.S. States That Are Technically Commonwealths As Massachusetts’ own government puts it, commonwealths are states, though the reverse is not true.1Mass.gov. Why is Massachusetts a Commonwealth?
The reason is structural. Article IV, Section 3 of the Constitution lets Congress admit new states but does not create tiers or categories among them.4Constitution Annotated. U.S. Constitution Article IV Section 3 Clause 1 – Admissions Once admitted, every state stands on equal footing: two senators, the same sovereign powers reserved by the Tenth Amendment, the same treatment in federal court.5Congress.gov. Tenth Amendment – Rights Reserved to the States and the People No commonwealth has ever successfully argued for different treatment because of its title.
The Two Commonwealth Territories
Puerto Rico and the Northern Mariana Islands round out the count. For these two, “commonwealth” carries genuine legal weight. The Department of the Interior defines a commonwealth territory as “an organized United States insular area, which has established with the Federal Government, a more highly developed relationship, usually embodied in a written mutual agreement.”6U.S. Department of the Interior. Definitions of Insular Area Political Organizations That distinguishes them from unincorporated territories such as Guam or the U.S. Virgin Islands, which have no such formal agreement.
Puerto Rico
Puerto Rico’s commonwealth status traces to Public Law 600 in 1950, which authorized Puerto Ricans to draft their own constitution. That constitution took effect in 1952 and set up the arrangement still in place today. U.S. citizenship for residents came earlier, under the Puerto Rican Federal Relations Act of 1917.7Office of the Law Revision Counsel. 48 USC 731 – Territory Included Under Name Puerto Rico
Northern Mariana Islands
The Northern Mariana Islands became a commonwealth through a formal covenant with the United States, approved by Congress in 1976 and fully effective on November 4, 1986.8Office of the Law Revision Counsel. 48 USC 1801 – Approval of Covenant to Establish a Commonwealth of the Northern Mariana Islands The covenant describes the islands as “a self-governing commonwealth … within the American political system.”
What the Word Actually Changes
The practical divide is sharp. Residents of the four commonwealth states live under the full Constitution, vote for president, and send voting members to Congress like any other Americans.
Residents of the two commonwealth territories do not. Both Puerto Rico and the Northern Mariana Islands remain subject to Congress’s broad authority under the Territorial Clause, which lets Congress legislate directly on a territory’s local affairs.9Congress.gov. ArtIV.S3.C2.3 Power of Congress over Territories Their residents are U.S. citizens who cannot vote in presidential elections and have no voting representation in Congress. Taxation runs differently too. Puerto Rico residents whose income comes only from Puerto Rico sources generally do not file U.S. federal income tax returns, though they still pay into Social Security and Medicare.10IRS. Topic No. 901 – Is a Person With Income From Sources Within Puerto Rico Required to File a U.S. Federal Income Tax Return The Northern Mariana Islands operates its own income tax system, based partly on the Internal Revenue Code and partly on locally imposed taxes.11IRS. Commonwealth of the Northern Mariana Islands (CNMI) Tax Credits
So the “commonwealth” label for a territory does signal a step above ordinary territorial status, with a written agreement and greater local self-governance than unincorporated territories have. It still falls well short of statehood.
Why the Four States Picked the Word
The word comes from the English “common weal,” meaning the shared well-being of the public. By the 1600s, English writers were using “commonwealth” for a government organized around the collective good rather than a monarch’s personal authority. When the American colonies broke from Britain, leaders in Virginia, Pennsylvania, and Massachusetts chose the term to signal that their new governments belonged to the people.
Virginia went first. Its 1776 constitution ordered that all commissions and grants run “in the name of the Commonwealth of Virginia.”2Encyclopedia Virginia. The Constitution of Virginia (1776) Pennsylvania followed months later, treating “commonwealth” and “state” as interchangeable in its September 1776 charter.12Yale Law School Avalon Project. Constitution of Pennsylvania – September 28, 1776 Massachusetts formalized the title in 1780, declaring that its people agreed “to form themselves into a free, sovereign, and independent body-politic or state, by the name of The Commonwealth of Massachusetts.”13University of Chicago Press. Fundamental Documents – Massachusetts Constitution Kentucky was the latecomer, entering the Union on June 1, 1792, as the fifteenth state and carrying forward the political traditions of Virginia, from which it had separated.14UKnowledge. Kentucky’s Road to Statehood
Two centuries later, the choice remains a matter of history and ceremony for those four states. The count of six commonwealths in the United States holds because two territories borrowed the same word for something entirely different.