Origins of Memorial Day - May 28

1864	Boalsburg, Pa. Women put flowers on the graves of their own Civil War dead (from the nearby battle of Gettysburg) and on other war dead in summer and fall. This is the start of their decorating the graves every year. August 1868, Boalsburg chapter of GAR organized and takes responsibility for yearly observance.
April 1865	A descendent of President John Adams, Mrs. Sue Landon Vaughn, is said to have led some women to Vicksburg, Mississippi, cemetery to decorate the graves of soldiers. 1954
May 1865	Winchester, Virginia. Local women form the Stonewall Jackson Memorial Association and decorate all the graves in the Confederate Cemetery, which is supposedly the first cemetery established for soldier dead in the South.
April 1866	Women of Columbus, Mississippi, go to "Friendship" Cemetery, on outskirts of the city, the burial ground for the Shiloh battle dead, and lay flowers on both Union and Confederate dead. Greeley's New York Tribune prints a story on the unprejudiced acts of these women that lead to widespread interest in impartial offering to memory of the dead. It is seen as a "healing touch for nation." Carbondale, Illinois. Inspired by seeing a woman with two children putting flowers on graves in rural Hiller Cemetery, just outside Carbondale, Ambrose Crowell, Russell Winchester, and Jonathan F. Wiseman clean and decorate other graves that day; then organize a wider-scale memorial observance at the larger Carbondale Woodlawn Cemetery on 29 April 1866. 219 Civil War veterans march to the cemetery, Southern Illinois' own Major General John A. Logan gives the principal address. Sexton James Green makes memo of the occasion on a flyleaf of old family book, complete with date, location, etc. Carbondale, therefore makes the claim of the first organized, community-wide Memorial Day observance in United States. In 1866 Carbondale Memorial Association, Inc. starts movement to establish its "first" claim. Illinois Congressman Kenneth Gray introduced House Bill No. 12175 to this end, to make Carbondale's Woodlawn Cemetery a national landmark.
May 1866	5 May, Waterloo, New York. Formal Memorial Day observations held. (see entry for May 1966)
1867	These activities inspire a young lawyer (later prominent jurist and co-founder of Cornell University) Francis Miles Finch to write the poem ''The Blue and the Gray, published in Atlantic Monthly September 1867. This work became very popular and contributed to the movement for a special day to decorate graves of the soldiers.
May 1868	In 1868 a former Union soldier from Ohio, name unknown, wrote to the Adjutant-General N.P. Chipman of the Grand Army of the Republic, an organization of Union veterans, suggesting an annual practice of honoring dead of Civil War with ceremonies and decorating of graves. The AG takes the suggestion to General Logan, the commander-in-chief of GAR, and on 5 May 1868 Logan directs local posts of the GAR to establish May 30 for this purpose. General Orders, No. 11, Headquarters, Grand Army of the Republic, Washington, D.C. 5 May 1868, proclaims ..."The 30th day of May, 1668, is designated for the purpose of strewing with flowers, or otherwise decorating the graves of comrades who died in defense of their country...." Arlington, Virginia, 30 May. Congressman James A. Garfield (later to become President) is first speaker at ceremony at National Cemetery at Arlington, Virginia. First formal and official observance of Memorial Day.
1873	Memorial Day is recognized as an official holiday, when New York State designates it as a legal holiday. Other states soon follow.
1882	The Grand Army of the Republic urges that the name of the holiday be "Memorial Day". Many, however, persist in calling it "Decoration Day", because of the way it began, with the decoration of the graves of fallen soldiers.
1887	Joint Resolution 6, 23 February 1887 (24 Stat. 644), U.S. Congress allows the day of each year which is celebrated as "Memorial" or "Decoration" Day to be a holiday for all per diem employees of the Government, on duty at Washington or elsewhere in the United States.
1888	Act of Congress, 1 August 1888 (25 Stat. 353) made 30 May a legal holiday for all persona in the District of Columbia.
1901	Act of Congress, 3 March 1901 (31 Stat. 1404) provided that if this day falls on a Sunday the next succeeding day shall be a holiday. Amended by the Act of 30 June 1902 (32 Stat. 543).
1926	Joint Resolution, 19 June 1926, U.S. Congress, authorizes and directs Secretary of War to accept a tablet commemorating the designation of 30 May as Memorial Day by General Orders 11, 5 May 1868, Headquarters of the Grand Army of the Republic, Signed by General John A. Logan, Commander-in-Chief.
1966	House Concurrent Resolution 587, 10 February 1966, introduced by Congressman Samuel S. Stratton, 89th Congress, 2d Session, recognized the village of Waterloo, New York's celebration on 5 May 1866 as the "first observance of Memorial Day as a national holiday to pay tribute to those who gave their lives in all our Nation's wars." The resolution also states that Congress does "recognize Waterloo, New York, as the birthplace of Memorial Day". It further states that while "Memorial Day has since become a national holiday, observed from one end of the land to the other on May 30", the President is requested to issue a proclamation calling attention to the centennial anniversary of the first observance of Memorial Day.
January 1971	With the passage of the "Monday Holiday Law", the celebration of Memorial Day Holiday is changed from 30 May to the last Monday in May.
December 2000	"National Moment of Remembrance" resolution, which asks that at 3 p.m. local time, for all Americans "To voluntarily and informally observe in their own way a Moment of remembrance and respect, pausing from whatever they are doing for a moment of silence or listening to 'Taps" was passed.

Source
http://www.army.mil/cmh-pg/faq/memday/MD-Dev.htm