During its first years as a country, the United States was governed by a parliamentary system of government. The Congress of the Confederation enacted all legislation, and one of its elected members was designated President of the United States in Congress Assembled, who served a one-year term. That changed in 1789 when the Constitution of the United States came into effect. George Washington was elected first President of the United States under the new constitution February 4, 1789. He began serving on April 30, 1789.