Although now known mostly as a three-day weekend to Bar-b-que and chance to buy big-ticket items on sale, Memorial Day originally had much more serious origins.
After the start of the American Civil War, commuities would set aside one day a year to decorate their fallen soldiers’ graves. On this day, which could be randon, townspeopl would gather to remember and honor those who fought for their country; which at the time, of course, could have been either the Union or Confederate States of America since both the North and the South engaged in this practice.
On May 30, 1868, Decoration Day (precurser to Memorial Day) was officially observed. It was proclaimed by General Jophn Logan to be a day to decorate the graves of Union and Confederate soldiers. May 30 was chosen because it was not an anniversary of a particular battle. While the day was meant to commemorate both sides of the conflict, many Southern states honored their dead on other days.
It was not until World War I that Decoration Day morphed into a day of rememberance for all fallen US servicemen (and later women.)
Memorial day was still celebrated on May 30th until 1971 when it was declared to be held on the last Monday in May in order to provide a better holiday for Federal employees.
If you get the chance, decorate the grave of a fallen soldier, hug a person in military service, or at least take a minute to remember those who gave their lives.
I found this information on the two following sites.