Arthur Alonzo Gilley was born on August 8, 1886 to Adelbert O. and Julia I. (Moore) Gilley in Tremont, Maine. Arthur married Mildred I. Robertson (1888-?), daughter of Aaron Jr. and Nancy J. Robertson on October 14, 1908 in Mount Desert, Maine. Arthur was a barber, like his father, in Southwest Harbor at the time of the 1909 census and as late as 1914. By the 1920 census he owned his own barber shop in Bath, Maine.
Arthur Alonzo Gilley (1886-) was a great great grandson of William Gilley (1746-1839).