20 August 1955 – Flying a U. S. Air Force North American F-100 C Super Sabre, Horace A. Haines sets a world speed record of 822.135 mph (1,323.889 km/hr). 
Colonel Horace A. Hanes, United States Air Force, flew the first North American Aviation F-100C-1-NA Super Sabre, 53-1709, to Mach 1.246 at 40,000 feet (12,192 meters), setting a new Fédération Aéronautique Internationale (FAI) speed record of 1,323.312 kilometers per hour (822.268 miles per hour) over a measured 15/25-kilometer course at Edwards Air Force Base, California.¹
This was the first supersonic world speed record. It was also the first speed record set at high altitude. Previously, all speed records were set very close to the ground for measurement purposes, but with ever-increasing speeds, this practice was becoming too dangerous.
For his accomplishment, Colonel Hanes was awarded the Mackay Trophy.
Source: Wikipedia Aviation Portal, ThisDayinAviation by Bryan R. Swopes