As President Joe Biden prepares to leave the White House on Monday, he will carry out a tradition observed by his predecessors: leaving a letter for the incoming president. The handwritten note, addressed to President-elect Donald Trump, will be placed on the Resolute Desk in the Oval Office before Biden departs, according to reports.

The practice of leaving letters between outgoing and incoming presidents dates back to Ronald Reagan, who left a lighthearted message for George H.W. Bush in 1989. Since then, the notes have grown more substantive, with each president using the gesture to offer advice, encouragement, or reflections. Biden himself received a letter from Trump four years ago, which he described as “very generous” but has not disclosed publicly.

While Biden prepares for his exit, Trump spent the evening before his inauguration addressing a rally in Washington, D.C., where he outlined his vision for the next four years. Promising to reverse many of Biden’s policies, Trump declared, “Tomorrow at noon, the curtain closes on four long years of American decline, and we begin a brand-new day of American strength and prosperity.”

The exchange of letters is one of the few bipartisan customs that remains intact in an increasingly divided political climate. Although Trump broke with tradition in 2020 by skipping Biden’s inauguration, he still honored the practice by leaving a note in the Oval Office. Reagan’s humor-filled letter, written on stationery adorned with a cartoon turkey, contrasts sharply with the weightier tone of recent exchanges, which reflect the challenges and complexities of modern presidencies.

As Biden prepares to leave the highest office, his note is expected to symbolize a peaceful transition, despite the contentious political landscape. The contents of the letter, however, may remain a mystery, continuing the unwritten rule that these messages are personal reflections left for the eyes of the new president alone.