In 1922, Dunlop was residing in Boston, working as a real estate, mortgage and insurance broker. He was married to Alice Lillian Hall, whom he wed on October 25, 1899, and had two children, Lydia and John William, Jr.. He later entered in a partnership with Stephen W. Sleeper, a fellow Harvard alumnus, to form the real estate firm Sleeper & Dunlop. He died at Westborough, Massachusetts in 1957.[1]