Article 2 Section 1 dictated the selection of the President of the United States by chosen electors from each of the states:
The executive Power shall be vested in a President of the United States of America. He shall hold his Office during the Term of four Years, and, together with the Vice-President chosen for the same Term, be elected, as follows:
Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress: but no Senator or Representative, or Person holding an Office of Trust or Profit under the United States, shall be appointed an Elector.
Although registered voters in the United States may vote for individuals for the office of the Presidency, the electors actually have the constitutional power to select the President of the United States. More information regarding this selection procedure is available from the National Archives & Records Administration US Electoral College.