The fire engine itself is reduced to an abstracted form composed of red rectangles, but there is a hint of a ladder on the right side and an axle across the bottom.

Demuth conveyed his friendship with Williams by incorporating fragments of his name: "Bill" across the top, and "CARLO" (the "O" cut off and the "S" missing entirely) in yellow dots as in an illuminated theater sign.

Janson mentions Demuth's interactions with Cubist painters in New York, and the connections between Futurism and Precisionism styles.

This portrait series is often described as also including writers Marsden Hartley, Gertrude Stein, Eugene O'Neill and Wallace Stevens, but those four were never completed.

The Yale University Art Gallery has the preliminary sketch, in watercolor and graphite, for the Marsden Hartley portrait.

Roberta Smith described the work in The New York Times: "Demuth's famous visionary accounting of Williams, I Saw the Figure Five in Gold, [is] a painting whose title and medallion-like arrangement of angled forms were both inspired by a verse the poet wrote after watching a fire engine streak past him on a rainy Manhattan street while waiting for Marsden Hartley, whose studio he was visiting, to answer his door.

"[7] Describing its importance, Judith H. Dobrzynski in The Wall Street Journal wrote: "It's the best work in a genre Demuth created, the 'poster portrait'.

[9] In March 2013, the US Postal Service issued a pane of 12 first-class postage stamps portraying modern art, one of which was Demuth's painting.