Answer:
He created, or established, the presidency. Except for these caveats, it is the substantial consensus among historians that Washington's tenure in office set the nation on a path that has endured now for over 200 years, longer than any other republic in history. He established precedents that would last for generations and did more to flesh out the skeleton of the presidential office than anyone could have expected or predicted. As one scholar has said, he "invented tradition as he went along." His actions, more than those of any other Founding Father, became a part of the "unwritten Constitution.
Also, although Washington hated partisanship and political parties, he tolerated dissent, vicious attacks on his reputation and name, and a divisive press—all in the interest of freedom. There is little reason to suggest that Washington, unlike so many of his successors, ever sought to use his office for personal empowerment or gain. Neither did he shelter his friends for the sake of their friendships when conflicts of interest arose.
Perhaps most importantly, Washington's presidential restraint, solemnity, judiciousness, and nonpartisan stance created an image of presidential greatness, or dignity, that dominates the office even today. He was the man who could have been a king but refused a crown and saved a republic.
