John Adams sworn in as first US Vice President (nine days before George Washington).

John Adams was a Founding Father and the second president of the United States from 1797 to 1801. Before his presidency, he was a leader of the American Revolution that achieved independence from Great Britain. During the latter part of the Revolutionary War and in the early years of the new nation, he served the Continental Congress of the United States as a senior diplomat in Europe. Adams was the first person to hold the office of vice president of the United States, serving from 1789 to 1797. He was a dedicated diarist and regularly corresponded with important contemporaries, including his wife and adviser Abigail Adams and his friend and political rival Thomas Jefferson.

The vice president of the United States is the second-highest ranking office in the executive branch of the U.S. federal government, after the president of the United States, and ranks first in the presidential line of succession. The vice president is also an officer in the legislative branch, as the president of the Senate. In this capacity, the vice president is empowered to preside over the United States Senate, but may not vote except to cast a tie-breaking vote. The vice president is indirectly elected at the same time as the president to a four-year term of office by the people of the United States through the Electoral College, but the electoral votes are cast separately for these two offices. Following the passage in 1967 of the Twenty-fifth Amendment to the US Constitution, a vacancy in the office of vice president may be filled by presidential nomination and confirmation by a majority vote in both houses of Congress.

April 21 is the 111th day of the year in the Gregorian calendar; 254 days remain until the end of the year.