The United States federal government designates national holidays for federal employees only. State and local governments generally observe these holidays as well as many State Holidays. For a basic list of holidays as seen on a 2008 calendar:

* January 1 New Year's Day
* January 21 Martin Luther King Jr. Day (3rd Monday of January, traditionally Jan. 15)
* February 2 Groundhog Day
* February 3 Super Bowl Sunday (currently the first Sunday of February)
* February 6 Ash Wednesday (Christian; moveable based on Easter)
* February 14 Valentine's Day
* February 18 Presidents Day (officially Washington's Birthday; 3rd Monday of February, traditionally Feb. 22)
* March 16 Palm Sunday (Christian; Sunday before Easter)
* March 17 St. Patrick's Day
* March 20 Vernal Equinox (based on sun), Lailatul-Qadr (Islamic; moveable, based on lunar calendar)
* March 21 Good Friday (Christian; Friday before Easter)
* March 23 Easter Sunday (Christian; moveable; Sunday after first full moon during spring)
* March 24 Easter Monday (Christian; Monday after Easter)
* April 1 April Fool's Day
* April 20 First day of Passover (Jewish; moveable based on Jewish calendar)
* April 21 Patriot's Day/Marathon Monday (New England and Wisconsin only) (3rd Monday of April)
* April 22 Earth Day
* April 27 Last Day of Passover (Jewish; moveable, based on Jewish Calendar)
* May 5 Cinco De Mayo (Mexican holiday often observed in US)
* May 11 Mother's Day (2nd Sunday of May), Pentecost Sunday (Christian; 49 days after Easter)
* May 26 Memorial Day (last Monday of May, traditionally May 30)
* June 14 Flag Day
* June 15 Father's Day (3rd Sunday of June)
* June 20 Summer Solstice (based on sun)
* July 4 Independence Day
* September 1 Labor Day (first Monday of September)
* September 2 First day of Ramadan (Islamic)
* September 30 - Oct. 1 Rosh Hashanah (Jewish; moveable, based on Jewish calendar)
* October 2 Eid-al-Fitr/Last day of Ramadan (Islamic, moveable, based on lunar calendar)
* October 9 Yom Kippur (Jewish, moveable, 9 days after first day of Rosh Hashanah), Leif Erikson Day
* October 13 Columbus Day (2nd Monday of October, traditionally Oct. 12)
* October 14 First day of Sukkot (Jewish; moveable, 14 days after Rosh Hashanaah)
* October 20 Last Day of Sukkot (Jewish)
* October 22 Simchat Torah (Jewish; moveable, 22 days after Rosh Hashanah)
* October 30 Mischief Night
* October 31 Halloween
* November 1 All Saints Day, Day of the Dead (Mexico)
* November 4 Election Day (Tuesday after the first Monday of November)
* November 11 Veterans Day
* November 27 Thanksgiving (4th Thursday of November)
* November 28 Black Friday (Friday after Thanksgiving Day)
* December 7 Pearl Harbor Remembrance Day
* December 21 Winter Solstice (based on sun)
* December 22 First day of Hannukkah (Jewish; moveable, based on Jewish calendar)
* December 24 Christmas Eve (Christian)
* December 25 Christmas Day (Christian)
* December 26 First day of Kwanzaa (Kwanzaa is celebrated until January 1, 2009)
* December 29 Last day of Hannukkah (Jewish; moveable, based on Jewish Calendar)
* December 31 New Year's Eve

The federal holidays (which are days off from work for federal employees) are New Years Day, Martin Luther King Day, Presidents Day, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day, and Christmas. The official list can be found here (http://www.opm.gov/Operating_Status_Schedules/fedhol/index.asp). These holidays are not necessarily days off from work for private sector workers. Most private sector businesses close for only the "Big 6" holidays: New Years Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas Day. Many also close on the Friday after Thanksgiving (aka Black Friday), which is not an official holiday, but is commonly granted to private sector workers. Some private businesses may also close for one or more other federal holidays (most commonly either Martin Luther King Day, or Presidents Day).

When a federal holiday falls on Sunday, most federal workers who work a Mon-Fri workweek will observe the holiday on Monday. When a federal holiday falls on Saturday, most federal workers who work a Mon-Fri workweek will observe the holiday on Friday. Workers who normally work on Saturday (such as mail carriers) will observe the holiday on Saturday; Friday will be a regular work day.

In state and local governments, and in the private sector, practices vary when a holiday falls on Saturday or Sunday. In general, most states and private sector workers will observe a holiday that falls on Sunday on Monday. However, that is not universal. Some states and private sector workers will observe a Saturday holiday on Friday, but that is less common than observing the Sunday holidays on Monday. Occasionally, a state or private sector worker will observe a Saturday holiday on Monday, but that is even less common than Friday. Many state workers and private sector workers (in particular, employees at a bank normally closed on Saturdays) do not get any day off when a holiday falls on Saturday, and are "cheated" out of the holiday. Ocasionally, a floating holiday may be given in lieu of a Saturday holiday.