On the internet, you'll find many lists of red-haired US presidents, but I bet this one is the most complete.
Here are the red-haired American presidents we've found so far. Click on the names and you'll be redirected to their posts.
1) George Washington, 1st president
2) Thomas Jefferson, 3rd president
3) Andrew Jackson, 7th president, Democratic Party
4) Martin van Buren, 8th president, Democratic Party
5) Franklin Pierce, 14th president, Democratic Party
6) Ulysses S. Grant, 18th president, Republican Party
7) Rutherford B. Hayes, 19th president, Republican Party
8) Calvin Coolidge, 30th president, Republican Party
9) Dwight Eisenhower, 34th president, Republican Party
10) John F. Kennedy, 35th president, Democratic Party
And that's 10 of them! Since we are currently at 46th president, this means that roughly the 22% of them had red hair, which is huge, since, as you know, redheads are only the 2% of the world population. It's only the Scottish and Irish heritage of first Americans or there's something more? Ai posteri l'ardua sentenza, as the Italian writer Alessandro Manzoni put it. 😉
And, if in your country you had red-haired presidents, please let us know!
PS: according to some, Donald Trump too has (or, at least, had) red hair, but in photos taken when he was younger, it looks more light brown to me.