Memorial Day was officially proclaimed on 5 May 1868 by General John Logan, national commander of the Grand Army of the Republic, in his General Order No. 11,and was first observed on 30 May 1868, when flowers were placed on the graves of Union and Confederate soldiers at Arlington National Cemetery. The first state to officially recognize the holiday was New York in 1873. By 1890 it was recognized by all of the northern states. The South refused to acknowledge the day, honoring their dead on separate days until after World War I (when the holiday changed from honoring just those who died fighting in the Civil War to honoring Americans who died fighting in any war).
It is now celebrated in almost every state on the last Monday in May (passed by Congress with the National Holiday Act of 1971 (P.L. 90 – 363) to ensure a three day weekend for Federal holidays), though several southern states have an additional separate day for honoring the Confederate war dead: January 19 in Texas, April 26 in Alabama, Florida, Georgia, and Mississippi; May 10 in South Carolina; and June 3 (Jefferson Davis’ birthday) in Louisiana and Tennessee
article courtesy of Elev8.com