I've known this for years. But don't take my word for it, take the words of Al Neuharth, the founder of USA Today:
Our great country has had 43 presidents. Many very good. A few pretty bad. On Presidents Day next Monday, it's appropriate to commemorate them all.
I remember every president since Herbert Hoover, when I was a grade school kid. He was one of the worst. I've personally met every president since Dwight Eisenhower. He was one of the best.
A year ago I criticized Hillary Clinton for saying "this (Bush) administration will go down in history as one of the worst."
"She's wrong," I wrote. Then I rated these five presidents, in this order, as the worst: Andrew Jackson, James Buchanan, Ulysses Grant, Hoover and Richard Nixon. "It's very unlikely Bush can crack that list," I added.
I was wrong. This is my mea culpa. Not only has Bush cracked that list, but he is planted firmly at the top.
Read the rest of Al's article here.