Third Monday in January Birthday of Martin Luther King, Jr., or Martin Luther King Day Honors Martin Luther King, Jr., Civil Rights leader; combined with other holidays in several states (traditionally January 15). This year's observance: 2008 - January 21

January 20, every fourth year, following Presidential election Inauguration Day Observed only by federal government employees in Washington D.C., and the border counties of Maryland and Virginia, in order to relieve congestion that occurs with this major event. Swearing-in of President of the United States and Vice President of the United States. Celebrated every fourth year. Note: Takes place on January 21 if the 20th is a Sunday (although the President is still privately inaugurated on the 20th). If Inauguration Day falls on a Saturday or a Sunday, the preceding Friday or following Monday is not a Federal Holiday

late January or February (date varies) Chinese New Year The start of the new year in the lunar calendar, often associated with China or other Asian nations and a time to celebrate their cultures.

January 7 Christmas (Orthodox) Christmas Day as celebrated in the Orthodox tradition.

February Black History Month Celebrating the contributions and culture of Afro Americans (Black Americans) (U.S. Citizens descended from Africa) throughout U.S. History.

February 2 Groundhog Day Prediction from Punxsutawney, Pennsylvania groundhog on whether the country will have six more weeks of winter.

February 14 Valentine's Day Traditional celebration of love and romance, including the exchange of cards, candy, flowers, and other gifts.

Third Monday in February Washington's Birthday Washington's Birthday was first declared a federal holiday by an 1879 act of Congress. The Monday Holiday Law, enacted in 1968, shifted the date of the commemoration of Washington's Birthday from February 22 to the third Monday in February. Many people now refer to this holiday as "Presidents' Day" and consider it a day honoring all American presidents. However, neither the Monday Holiday Law nor any subsequent law changed the name of the holiday from Washington's Birthday to Presidents' Day.[2] This year's observance: 2008 - February 18

February or March, date varies Mardi Gras and Ash Wednesday A festive season (Carnival) leading up to Shrove Tuesday or Mardi Gras. Closes with Ash Wednesday (40 days before Easter, not counting Sundays), which starts the season of Lent in the Christian calendar.

March 17 St. Patrick's Day A celebration of Irish heritage and culture, based on the Catholic feast of St. Patrick. Primary activity is simply the wearing of green clothing ("wearing o' the green"), although drinking beer dyed green is also popular. Attending St. Patrick's Day parades has historically been more popular in the United States than in Ireland.

April 1 April Fools' Day A day to play tricks on family, friends, and coworkers, if so inclined.

late March or April (Date varies) (March 21 for 2008) Good Friday Commemorates the crucifixion of Jesus Christ by Pontius Pilate, believed by Christians to have taken place (traditionally) on April 3, 33 AD. Sometimes celebrated as a "Spring holiday" for Universities and schools in certain states.

Spring Sunday, date varies Easter Celebrates the Christian belief in the resurrection of Jesus. For Christians, Easter is a day of religious services and the gathering of family. Many Americans follow old traditions of coloring hard-boiled eggs and giving children baskets of candy. On the next day, Easter Monday, the President of the United States holds an annual Easter egg hunt on the White House lawn for young children. The holiday is also often celebrated as a nonsectarian spring holiday. Not generally observed by most businesses as it always falls on a Sunday. Most financial markets and some other businesses close on the Friday prior, Good Friday (which is a state holiday in many states). Roman Catholic and Protestant groups celebrate Easter on a different Sunday (most years) than Orthodox groups.

Wednesday of last full week of April Administrative Professionals Day A day for honoring secretaries and other administrative personnel, formerly Secretary's Day.

April 22 (varies by location and observance) Earth Day A day used to promote environmentalism.

Spring, date varies Arbor Day A day for the planting of trees, commonly the last Friday of April but depending on the climate of the state.

Last Monday in May Memorial Day Honors the nation's war dead; marks the unofficial beginning of summer. (traditionally May 30)

May 5 Cinco de Mayo Primarily a celebration of Mexican culture by Mexican-Americans living in the United States. Although this is the anniversary of the victory of the Mexican Army over the French at the Battle of Puebla in 1862, Cinco de Mayo is far more important in the USA than in México itself. Additionally, this "holiday" is often mistaken by Americans as being Mexican Independence Day, which is actually observed on September 16.

Second Sunday in May Mother's Day Honors mothers and motherhood (made a "Federal Holiday" by Presidential order, although most Federal agencies are already closed on Sundays)

Third Saturday in May Armed Forces Day Celebrates the United States Army, Navy, Air Force Marine Corps and Coast Guard; formerly, each had separate days.

June 

June 14 Flag Day Honors the American flag, encourages citizens to fly the flag and study its traditions.

June 19 Juneteenth Primarily an African-American holiday, honors the end of slavery in the United States.

Third Sunday in June Father's Day Honors fathers and fatherhood.

July 4 Independence Day Celebrates Declaration of Independence, also called the Fourth of July.

First Monday in September Labor Day Celebrate the achievements of workers and the labor movement, marks the unofficial end of summer.

September or October (depends on Hebrew calendar) Rosh Hashanah Traditional beginning of the Jewish High Holidays. It is also celebrates the beginning of a new year on the Hebrew calendar.

September or October (depends on Hebrew calendar) Yom Kippur Traditional end of and highest of the Jewish High Holidays.

September, first Sunday after Labor Day Grandparents Day Honors grandparents.

Second Monday in October Columbus Day Honors Christopher Columbus, traditional discoverer of the Americas. In some areas it is also a celebration of Italian culture and heritage. (traditionally October 12); celebrated as American Indian Heritage Day and Fraternal Day in Alabama;^[1] celebrated as Native American Day in South Dakota.^[2]

October 12 Columbus Day Honors the first European explorer known to have set foot on North America.

October 31 Halloween Celebrates All Hallow's Eve, decorations include jack o'lanterns, costume wearing parties, and candy such as candy corn are also part of the holiday. Kids go trick-or-treating to neighbors who give away candy. Not generally observed by businesses.

first Tuesday after the first Monday in November Election Day Observed by the federal and state governments in applicable years; legal holiday in some states.

Saturday that follows November 9 Sadie Hawkins Day This was a day when women would ask men for dates, usually to a dance or other social, breaking with tradition. Named for the character "Sadie Hawkins" from the long-running comic strip Li'l Abner.

Second Monday in October Columbus Day Honors Christopher Columbus, traditional discoverer of the Americas. In some areas it is also a celebration of Italian culture and heritage. (traditionally October 12); celebrated as American Indian Heritage Day and Fraternal Day in Alabama;^[1] celebrated as Native American Day in South Dakota.^[2]

Fourth Thursday in November Thanksgiving Day Traditionally celebrates the giving of thanks for the autumn harvest. Traditionally includes the consumption of a turkey dinner Traditional start of the "holiday season." (Note: Thanksgiving is not celebrated on the same day as it is in Canada).

December 25 Christmas Day Celebrates the Nativity of Jesus which (traditionally) took place 25 December 1 BC. Some people consider aspects of this religious holiday, such as giving gifts and decorating a Christmas tree, to be secular rather than explicitly Christian.

December 26 through January 1 Kwanzaa African American holiday celebration created in 1966 by Dr. Maulana Ron Karenga.