The Structure of the National Government
The first national framework of the United States government, the Articles of Confederation, took effect in 1781 and established only one branch of government. Over the course of the first few years of the new nation, it became clear that this system was not meeting the needs of the people. Under the Articles, Congress was responsible for all the government’s duties—legislative, administrative, and judicial. To meet the needs and expectations of the American people, the United States would require what many Founders termed an "energetic” government. By this they meant a government equipped to protect Americans against internal and external threats; to secure trade and commerce; and to maintain and protect individual rights.
In 1787, fifty-five men gathered in Philadelphia to determine a new national structure of government. This new structure consisted of three branches instead of just one, and diffused power by delegating different responsibilities to each branch. The three branches are described and defined in the first three articles of the Constitution.