Only is a lonely word. It sets people apart and places them at a back-of-the-cafe table for one. When speaking of the 43 men who have been president of the United States — a rarefied roster already — the word only is extra-exclusive.
Some of the presidential onlies are well-known. Barack Obama is the only African-American president. Gerald Ford is the only president to have also served as vice president without having been elected to either office. He is also the only president from the state of Michigan. Richard Nixon is the only American president to resign from the office. Franklin Roosevelt is the only one to be elected to a third term. James Buchanan, the only president from Pennsylvania, is also the only president who never married. And so on...ly.
Here are some other, perhaps lesser-known presidential onlies. You only have to name the president.
Who was the only American president to ...
1) Preside over a meeting of the United Nations Security Council?
2) Also serve as ambassador to France?
3) Get married in the White House?
4) Serve nonconsecutive terms?
5) Be awarded a patent?
6) Face enemy fire while in office?
7) Also serve as a chief justice of the Supreme Court?
8) Choose to "affirm" his oath of office, rather than "swear"?
9) Father twins?
10) Earn a Ph.D.?
Bonus: Who was the only American president to not live in the White House?
Answers (linked to sources):
1) Barack Obama
10) Woodrow Wilson
Bonus: George Washington