The X-5 is one of a series of five paintings inspired by Charles Demuth’s I Saw the Figure Five in Gold (1928), which in turn was inspired by William Carlos Williams’ poem “The Great Figure” (1921). The work was Indiana’s first all-black, white, and gray painting, a departure from the general polychromy of his paintings and constructions. The following year he would employ the palette in two other paintings that were also an homage to both a painter (Joseph Stella) and a poet (Hart Crane), The Brooklyn Bridge and To the Bridge.
The painting is one of four works, along with USA 666 (The Sixth American Dream) (1964–66), USA 666 II (1966–67), and The X-7 (1998), that employs an X-shaped canvas. The shape is reminiscent of railway crossings, of cautionary signs, and as such evokes danger, relating it to The Beware-Danger American Dream #4 (1963) and works incorporating danger stripes, including The Sweet Mystery (1959–62).