Congress and the president have selected ten days as federal holidays. Being 'federal', these holidays technically only pertain to federal employees and residents of the District of Columbia, although they are so widely observed that they can be thought of as national holidays.
Officially, it is up to each individual state to select public holidays. If the holiday falls on a Saturday or Sunday, the Friday before or the Monday after is given in lieu to make a long weekend.
New Year's Day (January 1) - celebrating the New Year dates back to pre-Christian times, when rites were performed to try to ensure the return of Spring.
Martin Luther King Jnr. Day (third Monday in January) - before he was shot dead in 1968, Martin Luther King Jnr. was the foremost civil rights leader in the 1950's and 1960's. He was awarded the Nobel Peace Prize in 1964. Congress set this day aside to commemorate his life and accomplishments in 1983.
Washington's Birthday (third Monday in February) - originally it was celebrated on Washington's actual birthday, the 22nd of February, but it was moved in 1971 to make a long weekend. It is sometimes known as Presidents' Day, because it is near Lincoln's birthday on the 12th February.
Memorial Day (last Monday in May) - also called Decoration Day, it honours soldiers fallen in battle.It originates from the Civil War and is traditionally marked by parades and services.
Independence Day (4th July) - this, the most important US holiday, marks the 1776 signing of the Declaration of Independence from Great Britain. It was first commemorated in 1777 and is marked by fireworks, parades and speeches.
Labor Day (first Monday in September) - this, the suggestion of Peter J. McGuire, the president of the United Brotherhood of Carpenters and Joiners, was taken up in 1894 to celebrate American workers.
Columbus Day (second Monday in October) - Christopher Columbus and his crew landed in the Bahamas on Oct 12th 1492. It was first celebrated in 1792, although it was not officially recognized until 1909. It is a cause of special pride to Italian-Americans, who claim the Genoan explorer as their own.
Veterans Day (Nov 11th) - or Armistice Day commemorates the end of the First World War on Nov 11th 1918. It was made a legal holiday in 1938, but its name was changed in 1954 to honour all American veteran soldiers.
Thanksgiving Day (fourth Thursday in November) - it was first celebrated in Plymouth County, Massachusetts in 1621, the year in which the Pilgrims landed in the New World to give thanks for the new harvest and the new land they had colonized. President Lincoln made it a holiday in 1863.
Christmas Day (December 25th) - Christians celebrate the birth of Jesus Christ.