Introducing "The Presidents" ~ Who was the First?

I was unanimously elected as president and have been the only president ever unanimously elected.  

I also never accepted a salary for being President.  

I was a surveyor, talented horseman, and loved to write letters.  

I commanded the Continental Army, and I became the first President of the United States when I was 57 years old.  

My face is one of four carved into Mount Rushmore.  

Who am I?

George Washington
1st President of the United States
In Office
April 30, 1789 - March 4, 1797
Vice President - John Adams