Robert Indiana kept a series of illustrated journals during the late 1950s and 1960s, in which he discusses the development of his work as well as his daily life on Coenties Slip.

Indiana's journal page from December 13, 1961, includes a sketch of a detail from The American Gas Works, with a note that he added a second coat of cadmium red light to the painting. He then describes spending "a smooth day in the country: long figures. Total engrossment," a reference to the class he was teaching at the Scarsdale Studio Workshop, in the New York suburb of Scarsdale. He also records having dinner at Grand Central with J. (fashion designer John Kloss), taking a cab back downtown, and having Jim Rosenquist, who mentioned a studio visit by Jasper Johns, over.