He moved to
Denver, Colorado, in 1905 and worked as grocery clerk, sign painter, and salesman. He engaged in the automobile and oil business since 1905. Gillespie founded Power Equipment Company and incorporated under the corporate laws of Colorado on September 14, 1936. Operations were initially conducted through two affiliated corporations, Power Equipment Co. and Dean Gillespie & Co., which firms controlled the franchises for Allis-Chalmers Construction Equipment and White Motor trucks. Gillespie was elected as a
Republican to the
78th Congress to fill the vacancy caused by the death of
Lawrence Lewis, reelected to the
79th Congress, and served from March 7, 1944, to January 3, 1947. He was an unsuccessful candidate for reelection in 1946 to the
80th Congress. He then returned to his former business pursuits. He was president of Dean Gillespie & Company, president of Motoroyal Oil Company, and vice president of BluHill Food Corporation. He was an Elk, Mason, Shriner and a member of a number organizations. ==Personal life==