Cardinal Two belongs to Indiana’s Cardinal Numbers series, which consists of ten 12-inch square paintings, ten 24-inch square paintings, and ten 60 by 50-inch canvases constituting a single work, The Cardinal Numbers. The entire series made its debut in Indiana’s 1966 solo show at the Stable Gallery, New York. The paintings, along with the other works in the show, were painted in red, green, and blue, a color combination he associated with his father, Earl Clark, who had been employed by Phillips 66. In an interview with Barbaralee Diamonstein, published in 1979 in Inside New York’s Art World, Indiana explained:
"In the thirties, my father worked for Phillips 66, when all the Phillips 66 gasoline stations were red and green . . . when I was a kid, my mother used to drive my father to work in Indianapolis, and I would see, practically every day of my young life, a huge Phillips 66 sign. So it is the red and green of that sign against the blue Hoosier sky."
Cardinal Two was purchased by renowned collector Richard Brown Baker, who also conducted a series of interviews with Indiana in 1963. The work is currently in the collection of the Yale University Art Gallery, New Haven, Connecticut.