John McCullough, Presbyterian minister, son of John and Margaret (Fagg) McCullough, was born on his father's farm in Lower Oxford Township, Chester County, Pennsylvania, on April 3, 1805. He was a grandson of immigrant Scots from Ulster, Ireland. He attended Dr. Joseph Barr's Classical School and taught at Francis Latta's Moscow Academy. He entered Princeton Theological Seminary in 1830 but left in 1832 because of financial difficulties. McCullough married Lorena Sayre on October 12, 1831. He was licensed to preach by the New Castle Presbytery in 1833 and ordained by the Newton, New Jersey, Presbytery in 1835.
McCullough was fascinated by the drama of events in Texas and made his first trip to the republic in 1836. He went to Galveston in November 1838, with a commission from the Board of Foreign Missions and an annual salary of $200. He was elected chaplain of the Senate of the Third Congress of Texas. He organized the First Presbyterian Church in Galveston in January 1840 and was elected its first pastor. With William Y. Allen and Hugh Wilson, he organized the first Texas Presbytery on April 3, 1840. He was stated supply at Columbia-on-the-Brazos after October 15, 1841, but supported himself by teaching. In Columbia he planned mission work among the Mexicans in San Antonio; he made his first survey trip on horseback in 1842. From 1842 to 1845 he ran a school in the building that formerly housed the Texas House of Representatives. At that time two families and a few young men made up the entire Anglo population of San Antonio. With John W. DeVilbiss, McCullough held services in 1844 in the home of Juan Martín Veramendi. The following year the Board of Foreign Missions assigned McCullough as missionary to San Antonio. He began work in 1846 with a day school for Mexican children and the organization of the First Presbyterian Church. Though he was an ardent abolitionist in Pennsylvania, he came to accept Southern culture and the slaves of his wife's family, but he continued to preach for black congregations. Working against almost impossible difficulties and surviving attempts by desperados to assassinate him, he continued his efforts in San Antonio until after the death of his wife in 1849, when he returned to Galveston.
In his desire to help establish a Presbyterian college in Texas, McCullough obtained $500 in cash and a considerable number of books for the proposed institution, which was the nucleus of Austin College. Galveston Seminary, which he established in 1849, was a successful institution until it was forced to close by the yellow fever epidemic of 1854.
McCullough married Margaret Jane Riddell (see MCCULLOUGH, MARGARET JANE RIDDELL) in 1851 and subsequently spent several years in Ohio as stated supply for three churches near Zanesville. The family returned to Texas in 1859 and lived on a ranch near Double Horn in Burnet County until shortly before McCullough's death at Prairie Lea on January 9, 1870. Mrs. McCullough and her nine children returned to Galveston.