The United States national 21-gun salute is a gun for each state: for the president 21 guns, 17 for the vice-president, 15 for cabinet officers, governors, etc.
“Originally the president was saluted with as many guns as there were states in the Union. This idea was finally abandoned in the year 1819, when there were exactly 21 states, the commissioners deciding that hereafter 21 guns shall be the national presidential salute” – St. Louis Republic, MO. August 1893
