Presidential impeachment in the USA: How often has it happened?

Donald Trump would be joining a very small presidential club if he was ever to be impeached. Brad Sherman, a Democrat congressman from California, on July 12 became the first to launch official impeachment proceedings - although even he admitted it was a long way away. The embattled president has described calls for his impeachment as "ridiculous", saying he has done nothing to warrant criminal charges. He lashed out after days of political tumult, which culminated in the Jus