In what year did the Constitution become the law of the land?

American people began setting up a system of government as soon as they adopted the declaration of independence in 1776. However before the American revolution ended in 1783, each state had its independent constitution. In 1781 the states adopted the Articles of Confederation that established a federal government. Under these articles each state was supposed to work independently for it's own ends. However this system was found to be inadequate for effective functioning of the confederation. Therefore in 1787 delegates of all the states except Rhode Island met to consider revision of the Articles of confederation and  agreed to write a new constitution. After much debate, the delegates reached an agreement on the constitution on September 17, 1787. This constitution came into force when on June 21, 1788 New Hampshire became the ninth state to ratify it.

Bills of Rights, which forms a very important part of the present day American Constitution became a part of it  on December 15, 1791, when 10 amendments containing these rights became a law.