evidence: Donald Trump promised to give away his $400,000 presidential salary. And he kept that promise, publicly announcing each gift — at least, for his first 3½ years in office. Now, six months after he left office, it’s not clear where Trump donated that remaining salary — or if he donated it at all. [...] Trump first promised to forgo his salary in 2015, during the first months of his campaign. But the Constitution requires the president to be paid, so Trump chose to take the money and then give it back to specific federal agencies. Trump often said he was the first president to give away his salary, but he was wrong: Herbert Hoover and John F. Kennedy both did it previously.