Born in 1837 to Pennsylvania-Irish immigrants, John P. Colihan was the son of John and Ellen Colihan. The family settled in Middleport, Schuylkill County, where John worked as an 18-year-old coal mine engineer in 1860. He enlisted, with his brother Patrick, in the Ashland Rifles, April 21-July 25, 1861; saw limited action; later mustered in, Aug. 17, 1862 as a private, Co. K, 137th Regt., PVI– nine months; action at Antietam and Chancellorsville; mustered out, June 1863, and pursued the dry goods and grocery business in Ashland after the war, 1870 to 1885. Colihan emerged as a county Democratic boss in the late 1860s and was elected to the 30th Senatorial District, Schuylkill County, 1875-1876, appointed to the Mines and Accounts (Appropriations) Committees. In 1876, he supported the Bituminous Coal Health and Safety Act, establishing misdemeanor penalties for mine owners who neglected its provisions. He voted in favor of allowing defendants to testify in their own defense, important legislation during the Molly Maguire trials in Pottsville. On the other hand, he was also a supporter of the Philadelphia and Reading Railroad’s interests. The 1880 census indicates that he was a clerk in Washington, D.C.; and his wife’s name was Mary, age 43. The Senator died in 1885.