Hillman was born in Bangor, Maine on April 20-, 1902. He was graduated from Bangor High School in the class of 1921 and from Northeastern University in 1925.
For the next year and a half he ran a florist shop at the Copley Plaza Hotel in Boston and for one summer a similar shop at the Ocean House in Swampscott, Massachusetts.
Returning to Bangor, Hillman planned to build some greenhouses but went into the dairy business on his family’s farm and stayed with it most of his life as the owner and operator of Hillman’s Dairy, "Sunnydale Farms."
Never quite satisfied with being just a dairy farmer, he worked twelve years for the Federal Land Bank in Maine and during World War II worked for the Office of Defense-Transportation as an agriculture specialist for Maine.
Elected to the State Senate for four consecutive terms beginning in 1955, Hillman managed John H. Reed’s campaign for Senate President against an attempt to draft Robert N. Haskell for a third term.
Reed’s election propelled him to the Governorship and Hillman to the Senate Presidency for the 1960 Special Session. Elected to a full term as Senate President in 1961, Hillman was noted for his conservative and bulldog-like approach to politics.
Not a very polished man, he had difficulty with the nuances of presiding over the Senate. His persistence and straightforward approach, however, were admired by many. He became a controversial figure when he twice voted against permitting public transportation for parochial school pupils.
Resigning as Senate President in 1962 to become a member of the Public Utilities Commission, Hillman was reappointed by Governor Reed to a full seven-year term in December of that year.
Hillman died in Bangor on May 1, 1975 at the age of seventy-three.