The 21-gun salute honoring the President of the United States, like many American military traditions, appears to be another custom inherited from Great Britain. In early times, it was customary for a ship entering a friendly port to discharge its broadsides to demonstrate that they were unloaded; eventually it became a British practice to fire a seven-gun salute. The forts ashore would fire three shots for each shot fired afloat. The three guns fired on shore to one gun fired on ship had a practical explanation. In earlier days, gunpowder was made of sodium nitrate and was easier to keep on shore than at sea. When gunpowder was improved by the use of potassium nitrate, the sea salute was made equal to the shore salute. The use of numbers "seven" and "three" in early gun salutes probably was connected to the mystical or religious significance surrounding these numbers in many cultures.
Gun salutes continue to be fired in odd numbers, of course, and this is likely because of ancient superstitions that uneven numbers are lucky. As early as 1685, the firing of an even number of guns in salute was taken as indicating that a ship's captain, master, or master gunner had died on a voyage. Indeed, the firing of an even number of salute guns at the coronation of George VI in 1937 was regarded by at least one observer as an "ominous" portent. Incidentally, the normal interval of five seconds in the firing of gun salutes likely is in order for the salute to have full auditory effect, and also to give the salute a more solemn character.
The United States presidential salute has not always been 21 guns. In 1812 and 1821 it was the same as the number of states, i.e. 18 and 24, respectively, which was also our international salute. After 1841 the President received a salute of 21 guns and the Vice President 17; currently the Vice President receives a salute of 19 guns.
There has evolved over the last 175 years or so a prescribed number of guns, set forth in various Army regulations, to be fired for various dignitaries in accordance with the perceived importance of their positions. On 18 August 1875, the United States and Great Britain announced an agreement to return salutes "gun for gun," with the 21-gun salute as the highest national honor.
Today, a 21-gun salute on arrival and departure, with 4 ruffles and flourishes, is rendered to the President of the United States, to an ex-President, and to a President elect. The national anthem or "Hail to the Chief," as appropriate, is played for the President, and the national anthem for the others. A 21-gun salute on arrival and departure with 4 ruffles and flourishes also is rendered to the sovereign or chief of state of a foreign country, or a member of a reigning royal family. In these ceremonies, the national anthem of his or her country also is played.
Incidentally, U.S. Naval Regulations require that a 21-gun salute be fired at noon on Presidents Day, Independence Day, and Memorial Day.
USMC History Division