Military service members participating in the 42nd Annual U.S. Marine Corps Marathon-Forward take off from the starting line at at Al Dhafra Air Base, United Arab Emirates. Oct. 28, 2017. The official marathon, which was held in Virginia and Washington D.C., began in October 1975 and has grown to be the fourth largest marathon in the U.S. and the ninth largest in the world attracting upwards of twenty thousand runners each year. (U.S. Air Force photo by Staff Sgt. Colton Elliott)