Complex sentence: Many of these drawings exist today as a part of a Smithsonian collection in Washington, DC. Chickering was discharged from the Army in 1919, and census records for 1920 indicate that he resumed his career as a free-lance illustrator after the war.
Split into simpler sentences: Many of these drawings exist today as a part of a Smithsonian collection in Washington, DC. In 1919 he was discharged from the Army. According to 1920 census records he once again continued his career as a free-lance illustrator after the war.