Who was the last American president to have never left the country?

Every president since Theodore Roosevelt has traveled abroad either as president, or as president-elect.

Before TR, a number of presidents traveled abroad either for private travel, or diplomatic or military service (Washington, John Adams, Jefferson, Monroe, J.Q. Adams, W.H. Harrison, Taylor, Fillmore, Pierce, Buchanan, Grant, and B. Harrison). Jackson is an interesting case in that he traveled beyond US borders, but only traveled to places that later became part of the US.

There is no explicit evidence that the following presidents left the US, whether before, during or after their presidencies: Madison, van Buren, Tyler, Polk, Lincoln, Andrew Johnson, Hayes, Garfield, Arthur, Cleveland, and McKinley. Some of this is speculation, with incomplete records: Chester Arthur grew up near the Canadian border, and was rumored to have been born in Quebec, although historical investigations dispute this. But if this is correct, the last president to not travel outside the US, whether in his lifetime, or as president, was William McKinley.

Martin Van Buren as an unlikely international traveler is ironic, since he was the only President to speak English as a second language (he grew up speaking Dutch in New York).