The first president of the First Continental Congress, or of "the United States in Congress Assembled", was Peyton Randolph, who was elected on September 5, 1774.
then again it might be John Hanson in 1781!
The new country was actually formed on March 1, 1781 with the adoption of The Articles of Confederation. This document was actually proposed on June 11, 1776, but not agreed upon by Congress until November 15, 1777. Maryland refused to sign this document until Virginia and New York ceded their western lands (Maryland was afraid that these states would gain too much power in the new government from such large amounts of land). Once the signing took place in 1781, a President was needed to run the country. John Hanson was chosen unanimously by Congress (which included George Washington). In fact, all the other potential candidates refused to run against him, as he was a major player in the Revolution and an extremely influential member of Congress.
That confuses matters, doesn't it! ;-)