Question: The 1965 500cc United States Grand Prix was held at a racetrack opened in what year?

Context articles: Daytona International Speedway
Dick Creith
1968 Grand Prix motorcycle racing season
Hideo Kanaya
1972 Grand Prix motorcycle racing season
1965 Grand Prix motorcycle racing season
1962 Grand Prix motorcycle racing season
1970 Grand Prix motorcycle racing season
1964 Grand Prix motorcycle racing season
Buddy Parriott

Daytona International Speedway is a race track in Daytona Beach, Florida, United States.
 Since opening in 1959, it has been the home of the Daytona 500, the most prestigious race in NASCAR.
 In addition to NASCAR, the track also hosts races of ARCA, AMA Superbike, USCC, SCCA, and Motocross.
 The track features multiple layouts including the primary 2.5 mi high-speed tri-oval, a 3.56 mi sports car course, a 2.95 mi motorcycle course, and a 1320 ft karting and motorcycle flat-track.
 The track's 180 acre infield includes the 29 acre Lake Lloyd, which has hosted powerboat racing.
 The speedway is owned and operated by International Speedway Corporation.
Dick Creith (born August 28, 1938) was a former Grand Prix motorcycle road racer from Bushmills.
 He competed in only two Grand Prix races during his career, the 1964 and 1965 500cc Ulster Grand Prix.
 He won the 1965 500cc Ulster Grand Prix.
 He was also a two-time winner of the North West 200 race in Northern Ireland.
The 1968 Grand Prix motorcycle racing season was the 20th F.I.M. Road Racing World Championship Grand Prix season.
 The season consisted of ten Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc.
 It began on 21 April, with German Grand Prix and ended with Nations Grand Prix on 15 September.
 As the sidecar race was cancelled at the Nations Grand Prix, it was announced that a replacement race would be held at Hockenheimring in October alongside the German national championship.
Hideo Kanaya (Shinjitai: 金谷 秀夫 , Hideo Kanaya , February 3, 1945 – December 19, 2013) was a Grand Prix motorcycle road racer from Japan.
 Kanaya began his Grand Prix career in 1967 and won his first Grand Prix at the 1972 250cc German Grand Prix.
 In 1972, Kanaya and Jarno Saarinen raced the first four-cylinder, two-stroke Yamaha TZ 500 in the 500cc world championship.
 After Saarinen's death in the 250cc race at the Italian Grand Prix at Monza, the TZ 500 project was put aside and Kanaya raced only in the 250cc class.
 Kanaya's best season was in 1975, when he finished third in the 500cc world championship behind his Yamaha team-mate, Giacomo Agostini and MV Agusta's Phil Read.
 He also won the Macau Grand Prix in 1975.
The 1972 Grand Prix motorcycle racing season was the 24th F.I.M. Road Racing World Championship Grand Prix season.
 The season consisted of twelve Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc.
 It began on 30 April, with West German Grand Prix and ended with Spanish Grand Prix on 23 September.
The 1965 Grand Prix motorcycle racing season was the 17th F.I.M. Road Racing World Championship Grand Prix season.
 The season consisted of thirteen Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc.
 It began on 21 March, with United States Grand Prix and ended with Japanese Grand Prix on October, 24.
The 1962 Grand Prix motorcycle racing season was the 14th F.I.M. Road Racing World Championship Grand Prix season.
 The season consisted of eleven Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc.
 It began on 6 May, with Spanish Grand Prix and ended with Argentine Grand Prix on 14 October.
 Defending 350cc and 500cc world champion Gary Hocking was deeply affected by the death of his friend, Tom Phillis at the 1962 Isle of Man TT and, announced his retirement from motorcycle racing after winning the 1962 Senior TT.
 Hocking's MV Agusta teammate, Mike Hailwood went on to win his first 500cc world championship.
The 1970 Grand Prix motorcycle racing season was the 22nd F.I.M. Road Racing World Championship Grand Prix season.
 The season consisted of twelve Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc.
 It began on 3 May, with West German Grand Prix and ended with Spanish Grand Prix on 27 September.
The 1964 Grand Prix motorcycle racing season was the 16th F.I.M. Road Racing World Championship Grand Prix season.
 The season consisted of twelve Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc.
 It began on 2 February, with United States Grand Prix and ended with Japanese Grand Prix on 1 November.
Buddy Parriott was a professional motorcycle road racer.
 In the 1965 Grand Prix motorcycle racing season, he became the first American rider to finish on the podium in the premier class, when he finished in second place behind Mike Hailwood at the 500cc United States Grand Prix, held at the Daytona International Speedway.