I taught Jr High American history for many years and am always amazed at how Polk is so overlooked. He added Texas, Oregon Country, and the Mexican Cession to the U.S. fulfilling the idea of our nation stretching from sea to sea. And he did it in one term.
...and he promised to only serve one term....so he came, he saw, he conquered....and then left.
I went to his childhood home in North Carolina a few years ago. Pretty awesome.