The secret contents of former President Joe Biden's letter to Donald Trump were revealed by Peter Doocy, a Fox News correspondent, on X on Wednesday.

Ronald Reagan scribbled a note in 1989 to his successor above an elephant cartoon. The tradition, started perhaps inadvertently, was continued by Joe Biden.

What is clear is that after four contentious years, Biden leaves Washington as a remarkably consequential one-term president.

Ronald Reagan started a tradition as he prepared to leave office after two terms as president: Write a note congratulating your successor and leave it in the Oval Office desk drawer.

Eerie similarities between Joe Biden's hostage release deal and the deal made with Iran by former President Jimmy Carter do not go unnoticed.

A look at the history of presidential letters and whether President Biden will continue the tradition by writing a note for his predecessor-turned-successor, Donald Trump.

Donald Trump has revealed what Joe Biden wrote to him in his "inspirational" farewell letter. Trump found the letter in his desk on Monday, as he signed executive orders in the Oval Office. It is part of a tradition, started by President Ronald Reagan, which sees one president leave a welcome note to his successor.

Donald Trump shared details about a 'nice' and inspirational letter former President Joe Biden left for him at the White House Resolute Desk. The letter continues an inauguration tradition initiated by Ronald Reagan.

With all the attention, deservedly, on President Trump and what he intends to do with his defiant return to the White House, there’s a more than good chance we’ll spend the next four years consumed once again by all things Trump.

Read Biden’s farewell letter to Trump in full - Presidential tradition to leave letters for successors began with Ronald Reagan in 1989

After four years of a subdued term under President Joe Biden, 82, Trump has brought energy and unpredictability back to the Oval Office. The former reality TV star and businessman known for his branding, Trump, 78, jump-started his agenda with an eye for dramatics.