He was considered "one of the mainstays, one of the people who helped build the School of Art" and is an important modernist artist in Colorado.
His parents were of Russian-Jewish and German-Jewish background but the family was baptised in the Russian Orthodox Church for economic reasons.
[2] In 1921, the family left Rostov and emigrated to the United States, traveling on short-term visas via Kiev, Italy and Greece.
In 1928 he joined the Art Students League in New York to study with lithographer Charles Locke, but could not afford to continue.
[4] He also contributed to books and pamphlets of International Publishers, the printing arm of the Communist Party USA headed by Alexander Trachtenberg.
His works included the Newbery Honor Book The Jumping-Off Place by Marion Hurd McNeely; Yermak the Conqueror by P.N.
[3] In 1934, the New School of Social Research in New York City exhibited some drawings and possibly watercolors by Siegel as well as Anton Refregier.
[2] In March 1942, William Sanderson was drafted into the U.S. Army and sent to Kessler Field near Biloxi, Mississippi for basic training.
He had a solo show of black-and-white drawings of army life at the Denver Art Museum-Chappell House, and began painting watercolors.
In 1943 he met Ruth Lambertson of Cedar Falls, Iowa at the Colorado Springs Fine Arts Center.
Stylistically, he produced stylized realist and surrealist images, as well as a period of abstract expressionist works.
[2] He considered social criticism to be an important part of an artist's work, and was responsive to racial prejudice in works such as Whites Only and Brief Encounter and to Chicano social and political concerns in Tierra y Libertad (Land and Liberty) and La Pulqueria (Pulque Drinking).