Memorial Day was originally called Decoration Day. Memorial Day is a day to remember those who died in the service of the United States of America.
"General John A. LoganLibrary of Congress, Prints & Photographs Division, [LC-B8172- 6403 DLC (b&w film neg.)]
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."
Thanks to http://www.usmemorialday.org/backgrnd.html for the above information and quotation. The quote is a brief excerpt. Click this link to read the entire history of Memorial Day.