Joe Biden has wrapped up a more than 50-year political career. But he also promised that “we’re not leaving the fight,” as he bid farewell to the presidency and flew to California with his family to ease back into private life.

Every president since Ronald Reagan has left a note for his successor, and President Biden is the first to write a letter to someone who is both his successor and the predecessor who left a note for him.

The political rivals departed the White House together to travel to Capitol Hill for Trump's swearing-in ceremony. Flashback: This is the first time Biden and Trump have gone through many of the traditional motions during the transition of power,