New Year's Day, January 1 
Birthday of Martin Luther King, Jr. Third Monday in January 
Washington's' Birthday, Third Monday in February
Memorial Day, Last Monday in May 
Independence Day, July 4
Labor Day, First Monday in September
Columbus Day, Second Monday in October
Veterans Day, November 11
Thanksgiving Day, Fourth Thursday in November
Christmas Day, December 25 

Federal law (5 U.S.C. 6103) establishes the following public holidays for Federal employees. Please note that if the four holidays set by date (New Year's Day, Independence Day, Veterans Day or Christmas Day) fall on a Saturday, the holiday is usually observed on a Friday if the holiday falls on a Sunday -- the holiday usually is observed on a Monday. 

New Year's Day, January 1 
Birthday of Martin Luther King, Jr. Third Monday in January 
Washington's' Birthday/President's Day, Third Monday in February
Confederate Memorial Day, May 10
National Memorial Day, Last Monday in May
Independence Day, July 4
Labor Day, First Monday in September
Veterans Day, November 11
National Thanksgiving Day, Fourth Thursday in November
Day after Thanksgiving Day
Christmas Eve, December 24 (The Governor may declare this a state holiday)
Christmas Day, December 25 
Day after Christmas, December 26

http://www.scstatehouse.net/code/titl53.htm 

Purple Heart Day, third Saturday in February
South Carolina Day, March 18, public schools shall observe Calhoun's birthday
Golf week, last week in April
Loyalty Day, May 1st
Family Respect Day, Friday immediately preceding Mother's Day
Mother's Day, second Sunday in May
Garden Week, week beginning the first Sunday of June
Carolina Day, June 28
Family Week, last week in August; also "South Carolina Family of the Year" Award
Grandmother's Day, second Sunday in October

Read the law and what you should do to honor these days: