In the Washington Post, David Mayhew asks which was the most important presidential election in US history.
This is tough, because not all consequential presidencies derived from consequential elections. Roosevelt sailed to victory in 1932 and 1936, which respectively inaugurated and ratified the New Deal. It’s hard to feel the elections themselves were consequential, because they were nothing like close; it’s the surrounding circumstances and the appeal of Roosevelt’s reactions that were important; the presidency was won or lost before the actual election.
The 1860 election wasn’t close, so it’s more like 1932 that way. The 1960 election was very close, and maybe an earlier Nixon presidency would have made a big difference, but I’m not sure. A Dewey win in 1948 might well have mattered, but again, I’m not entirely sure.
I think the best match of consequential election – where the election itself determined who would go to the White House – to consequential presidency – where the person in the White House really shifted the course of history – was probably 2000.