The Federalists, mostly. Their arguments convinced enough states that the new Constitution, though not perfect, was a big improvement over the Articles of Confederation. Plus, the document could be amended, or changed. In fact, several states suggested amendments to the Constitution at the same time they voted to ratify it, notes Henry L. Chambers Jr., a law professor at the University of Richmond in Virginia.
“Clearly, those states were saying: This is a step along the way. We’re going to ratify, but we know we’re not done,” Chambers explains.
In December 1787, Delaware became the first state to approve the Constitution. Other states followed. In June 1788, New Hampshire became the ninth state to ratify—the last vote needed. On March 4, 1789, the date set by Congress, the Constitution officially became the law of the land.
Though they had not supported the Constitution, the Antifederalists did leave their mark on it. In 1789, the very first Congress under the Constitution agreed that it was important to protect Americans from too much government control. Two years later, the freedoms that Antifederalists had demanded became the first 10 Amendments to the Constitution, known as the Bill of Rights.