Presidential Underwear

It is well documented that Calvin Coolidge and John F. Kennedy wore union suits in their day. Button-down, long one-piece underwear was probably worn by most other presidents in the mid-to-late 19th century and much of the 20th century, from Abraham Lincoln to George H.W. Bush. "Mostly brief" wearing Bill Clinton may not have ever worn a suit. Neither, I'm guessing, did boxer shorts wearing Obama, Bush the younger, or Trump. There's a good chance Joe Biden has worn union suits, him being older and from Delaware. We'll never know for sure who among U.S. leaders of the executive branch actually wore union suits. Yet, there's a good chance these men did:

Ulysses S. Grant

Woodrow Wilson

And most of the Roosevelts including Theodore (Teddy) and his boys, Theodore Jr.,  Archibald, Kermit, and Quentin: