New Jersey's current state constitution was drafted by a convention of delegates from each county, convened from 12 June to 10 September 1947. The new charter further strengthened the Office of the Governor and reorganized and unified the judicial system under the Supreme Court.
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According to the National Archives:
"After three hot summer months of equally heated debate, the delegates appointed a Committee of Detail to put its decisions in writing. Near the end of the convention, a Committee of Style and Arrangement kneaded it into its final form, condensing 23 articles into seven in less than four days.
On September 17, 1787, 38 delegates signed the Constitution. George Reed signed for John Dickinson of Delaware, who was absent, bringing the total number of signatures to 39. It was an extraordinary achievement. Tasked with revising the existing government, the delegates came up with a completely new one. Wary about centralized power and loyal to their states, they created a powerful central government. Representing wildly different interests and views, they crafted compromises. It stands today as one of the longest-lived and most emulated constitutions in the world."
The National Archives maintains a webpage dedicated to the Constitution of the United States. There you can see a copy of the document, read a transcript, learn how it was made, who signed it, and more.
The National Constitution Center has a great deal of information on the Constitution, including a Constitution 101 course, a library of Supreme Court cases covering the most influential cases in American History, and many interactive and interpretive features. They sponsor Constitution Day on September 17 each year with education and entertainment activities. Stop by the New Jersey State Library to get a free pocket copy of the US Constitution and the Declaration of Independence.
The United States is not the only country to have a constitution. Likewise, New Jersey is not the only state to have it's own constitution.
Most US States provide online access to their constitutions. The Indiana University Bloomington, Jerome Hall Law Library has an interactive map to help you research constitutions in all 50 states. Here at the NJ State Library, you can use the Lexis and Westlaw databases to see each state's constitutions. You can use the HeinOnline database to access all of the state constitutions, plus additional materials to put those documents in historic and current context.
The Constitute Project provides access to many of the world's constitutions and gives researchers the ability to compare them. The CIA World Factbook provides information on many of the world's constitutions.