On September 17, 1787, the U.S. Constitution was signed by the members of the Constitutional Convention in Philadelphia, Pennsylvania. In December, 2004, Senator Robert C. Byrd offered an amendment in an attempt to increase knowledge of the constitution. All institutions that receive federal funding are required to provide educational programs relating to the United States Constitution—annually on September 17—the day marked to commemorate the signing of the constitution.
Constitution Day (sometimes called Citizen's Day) also serves as a reminder to citizens to participate in the political process by exercising their right to vote.
There are many great online resources available about the U.S. Constitution, including the National Constitution Center, which houses an online, interactive Constitution.