The Forth of July

The 4th of July has come around again.  Greetings of "Happy 4th", "Have a great 4th of July", etc..., permeate my ears.  This got me thinking, we generally refer to this holiday as the Forth of July as opposed to Independence Day.  We refer to this particular holiday by its calendar date, as opposed to the actual celebration behind the holiday.  Is this exclusive to the "The Forth" or does this phenomena spread to other holidays, commemorations, and/or anniversaries.  Enclosed below is a list, where the usual name is bolded.  Apparently, the name of the event rather than the date it occurs is used.  "The 4th" and "9/11" appear to be anomalies.  But why?  Imagine if we started calling Christmas, "December 25th", or Valentines, "February 14th"?  

Does the nomenclature of the event, rather by calendar date or name, deprecate or intensify the meaning behind the event?  Do we even know why we are celebrating/commemorating an event?  Or are most of the holidays just an extra day off?

Date	Official Name	Remarks
January 1	New Year's Day	Celebrates beginning of the Gregorian calendar year. Festivities include countdowns to midnight (00:00).
Third Monday in January	Birthday of Martin Luther King, Jr.	Honors Martin Luther King, Jr., Civil Rights leader; combined with other holidays in several states (King's birthday was January 15)
January 20, every fourth year, following Presidential election	Inauguration Day	Swearing-in of President of the United States and other elected federal officials. Observed only by federal government employees in Washington, D.C., and certain counties and cities of Maryland and Virginia, in order to relieve congestion that occurs with this major event. Note: Takes place on January 21 if the 20th is a Sunday (although the President is still privately inaugurated on the 20th).
February 14*	Valentine's Day	The traditional day on which lovers express their love for each other by sending Valentine's cards, presenting flowers, or offering confectionery.
Third Monday in February	Washington's Birthday	Honors George Washington. Often popularly observed as "Presidents Day" in recognition of other American presidents, such as Abraham Lincoln (who was born February 12). The legal name of the federal holiday, however, is "Washington's Birthday".(historically observed on February 22, prior to passage of the Uniform Monday Holiday Act by Congress)
Last Monday in May	Memorial Day	Also known as "Decoration Day", Memorial Day originated in the nineteenth century as a day to remember the soldiers who gave their lives in the American Civil War by decorating their graves with flowers. Later, the practice of decorating graves came to include members of ones own family, whether they saw military service or not. Memorial Day is traditionally the beginning of the summer recreational season in America. (historically observed on May 30, prior to the Uniform Monday Holiday Act)
July 4, The Forth	Independence Day	Celebrates the signing of the Declaration of Independence. More commonly known as "the Fourth of July".
First Monday in September	Labor Day	Celebrates achievements of workers and the labor movement. Labor Day traditionally marks the end of the summer recreational season in America. The following day often marks the beginning of autumn classes in primary and secondary schools.
Second Monday in October	Columbus Day	Celebrated since 1792 in New York City, honors Christopher Columbus, who landed in the Americas on October 12, 1492. In some areas it is also a celebration of Italian-American culture and heritage. Congress and President Franklin Delano Roosevelt set aside Columbus Day in 1934 as a Federal holiday at the behest of the Knights of Columbus (historically observed on October 12, prior to the Uniform Monday Holiday Act)
October 31	Halloween	Halloween activities include trick-or-treating, ghost tours, bonfires, costume parties, visiting "haunted houses", and carving jack-o-lanterns.
September 11, 9/11*	World Trade Center Bombing	Bombing of the World Trade Center
November 11	Veterans Day	Also known as Armistice Day, and very occasionally called "Remembrance Day", 'Veterans Day' is the American name for the international holiday which commemorates the signing of the Armistice ending World War I. In the United States, the holiday honors all veterans of the United States Armed Forces, whether or not they have served in a conflict; but it especially honors the surviving veterans of World War I, World War II, the Korean War, and the Vietnam War. The American holiday was briefly moved to the final Monday in October under the Uniform Monday Holiday Act, but the change was greatly disliked and soundly criticized - among other reasons, because it put Veterans Day out of sync with international observance; so it was restored to November 11.
Fourth Thursday in November	Thanksgiving Day	Traditionally celebrates giving thanks for the autumn harvest, and customarily includes the consumption of aturkey dinner. (historically observed on various days, but finally becoming so fixed to the fourth Thursday in November in the hearts and minds of Americans, that Americans rebelled (albeit politely) when President Franklin Delano Roosevelt attempted to move it to the third Thursday of November, at the request of numerous powerful American merchants)
December 25	Christmas Day	A holiday that celebrates the birth of Jesus Christ, observed on 25 December. Aspects of the holiday include decorations, emphasis on family togetherness, kindness and goodwill toward all people. Designated a federal holiday by Congress and President U.S. Grant in 1870.

table source: http://en.wikipedia.org/wiki/Federal_holidays

*inserted for refernce, not a federal holiday