Which state’s constitution, adopted in 1780, is the world’s oldest written constitution still in force?

The Massachusetts Constitution, adopted in 1780, is the world’s oldest written constitution still in force.

Massachusetts voters approved the constitution on June 15, 1780, and it took effect on October 25 of that year. John Adams drafted much of the document, including its influential structure of a declaration of rights followed by a framework of government.

The constitution divided state authority among legislative, executive, and judicial branches. It also established an elected governor, a feature that distinguished Massachusetts from several earlier revolutionary state arrangements. Its language influenced later constitutional thinking in the United States.

The document has been amended many times rather than replaced. That continuity is why it is described as the oldest written constitution still functioning in its original jurisdiction. It should not be confused with the United States Constitution, which was drafted in 1787 and took effect in 1789, or with the 1776 Massachusetts constitution that preceded the present document.