Who was the first President of US , this question is repeated in almost all the competitive exams. Before going into the answer Who was the president of United States of American. Office of the President in United States established in 1789 and till date 45 persons served as President . In 1789 George Washington unanimously elected as 1st President of US. Before joining as President George Washington served as Commander in Chief of the Continental Army from 1775 to 1783.