Volunteers to include U.S. Airmen assigned to Travis Air Force Base participate in a service project on Martin Luther King Jr. Day at Anna Kyle Elementary School in Fairfield, California, Jan. 21, 2019. Each year, on the third Monday in Jan., the MLK Day of Service is observed as a "day on, not a day off." (U.S. Air Force photo by Master Sgt. Joey Swafford)