With one of his final acts in office, President Joe Biden took part in the presidential tradition of writing a letter to his successor, President Donald Trump.
The tradition began with President Ronald Reagan leaving a letter for his own Vice President George H.W. Bush in 1989, with Bush carrying on the convention four years later after losing the 1992 election to President Bill Clinton. Every president since then - including Trump in 2021 - has left a letter for their successor.