Texas not the first IndyCar doubleheader

Indy Car Racing doubleheaders with race winners

USAC sanction

July 1, 1967: Mosport, Canada (road course; Bobby Unser and Bobby Unser)
Aug. 6, 1967: St. Jovite, Canada (road course; Mario Andretti and Mario Andretti)
June 15, 1968: Mosport, Canada (road course; Dan Gurney and Dan Gurney)
July 21, 1968: Indianapolis Raceway Park (road course; Al Unser and Al Unser)
July 28, 1968: Langhorne, Pa. (Al Unser and Al Unser)
Aug. 4, 1968: St. Jovite, Canada (road course; Mario Andretti and Mario Andretti)
July 27, 1969: Indianapolis Raceway Park (road course; Dan Gurney and Peter Revson)
Sept. 14, 1969: Brainard, Minn. (road course; Gordon Johncock and Dan Gurney)
Oct. 19, 1969: Kent, Wash. (road course; Mario Andretti and Al Unser)
Feb. 28, 1971: Rafaela, Argentina (Al Unser and Al Unser)
April 15, 1973: Trenton, N.J. (A.J. Foyt and Mario Andretti)
Sept. 16, 1973: Michigan International (Billy Vukovich and Johnny Rutherford)
Sept. 22, 1974: Trenton, N.J. (A.J. Foyt and Bobby Unser)

CART Sanction

April 22, 1979: Atlanta (Johnny Rutherford and Johnny Rutherford)
June 10, 1979: Trenton, N.J. (Bobby Unser and Bobby Unser)
July 15, 1979: Michigan International (Gordon Johncock and Bobby Unser)
June 28, 1981: Atlanta (Rick Mears and Rick Mears)

Note: "Twin" races were held as qualifying events for the Ontario 500 Mile Races of 1973, '74 and '75, but they employed odd and even qualifiers rather than all contestants together in the same races.