Assuming he serves out his new term and then retires (as required by the 22nd Amendment), President Obama will join a perhaps surprisingly short list of two-full-terms-and-out presidents.
It's true that Obama is the third consecutive president to be reelected, which may contribute to an impression that presidents serving two consecutive terms, then retiring, is the natural order of things. But that three-in-row streak for eight-year presidencies hasn't happened since the earliest days of the Republic, when America was briefly a sort of one-party nation and Thomas Jefferson, James Madison and James Monroe serve two terms each in succession.
But the impression of a two-term norm would be deceptive. Out of the 43 pre-Obama presidents (counting Grover Cleveland twice), just 11 served eight years. And five of those (Washington, Jefferson, Madison, Monroe and Jackson) were packed into the earliest period of presidential history. Especially in the long period between Monroe and Bill Clinton, the eight-year presidency was a relative rarity. Here are the only other two-full termers: Grant, Wilson, Eisenhower, Reagan, George W. Bush and Clinton.
Nine presidents were nominated for a second term but were defeated for reelection: John Adams, John Quincy Adams, Van Buren, Cleveland (although he came back to win a second non-consecutive term), Benjamin Harrison, Taft, Hoover, Carter and George H.W. Bush.
So serving two terms, and losing while trying for a second term still accounts for only 20 of the 44 presidencies. What happened to the others? Several things:
Four won one term then didn’t seek re-election (Polk, Buchanan, Hayes and Cleveland, after his comeback).
One was elected to one term, then tried but failed to win his party’s nomination for a second term (Franklin Pierce).
Five died during their first term (William Henry Harrison, Zachary Taylor, Garfield, Harding and JFK).
Two were reelected, then killed during their second term (Lincoln, McKinley).
One was reelected, then resigned during his second term (Nixon).
Four ascended from the vice presidency upon the death of their predecessor, won a single term in their own name, then declined to seek a second full term although they could have (Teddy Roosevelt, Coolidge, Truman, LBJ). Teddy Roosevelt changed his mind and made an unsuccessful comeback attempt. Truman served all but two months of FDR’s fourth, so he was an eight-year president, minus two months.
Five others ascended from the vice presidency but never won a term of their own (Tyler, Fillmore, Andrew Johnson, Chester A. Arthur and Gerald Ford). Of those, only Ford was nominated and defeated. Tyler and Fillmore sought their party’s nominated for a full term, but were defeated for nomination.
And one was elected four times (FDR, although he served less than two months of his fourth term).
This is the kind of thing history nerds like me do for fun.