Good grid - although I dont think Nixon technically belongs in his group

As Widger, says, Nixon does not qualify for his group, although he very likely would if he had remained President longer. More technically correct would be to replace "Nixon" with "Trump, again".

Nit picky on Nixon. He just dodged impeachment. Really good confusion with the assasination and Mt. Rushmore groups because you have enough names of people who have appeared on US coins and bills. I must admit to failing to solve it because Mt. Rushmore was so obvious that I never considered it and kept going on about assassinations and currency. Very well done.