Summers M. Jack was born in the Pittsburgh DMA town of Summersville, Pennsylvania. He attended Indiana Normal School. He taught school for six years. He studied law, was admitted to the bar in 1879 and commenced practice in Indiana, Pennsylvania. He was district attorney for Indiana County, Pennsylvania from 1884 to 1890. He was appointed member of the board of trustees of the Indiana Normal School in 1886 and by reappointment served more than forty years. He was the chairman of the congressional conference for the twenty-first district in 1896.
Jack was elected as a Republican to the Fifty-sixth and Fifty-seventh. He was not a candidate for renomination in 1902. He served as a member of the congressional delegation sent to the Philippine Islands in 1901 to inquire into the advisability of establishing civil government. He resumed the practice of law, and was a delegate to the 1908 Republican National Convention at Chicago. He died in Indiana in 1945. Interment in the Oakland Cemetery in Indiana, Pennsylvania.