His father, James O'Fallon, was a physician who came to this country shortly before the Revolutionary War and served as a surgeon in Washington's army.

After the war he went to Louisville, Kentucky, where he met and married Frances Clark, a sister of George Rogers Clark and William Clark, Army officers, who became famous in the development of the Mississippi Valley.

John O'Fallon's father died when John was but a child and he was reared and educated by his mother and uncles. With this army background it was only natural that he, too, became a soldier.

In 1811, John joined a force of mounted volunteers under Col. Joseph Hamilton Davies to take part in the war against the Indians in Indiana Territory. He also fought in the War of 1812 under General William Henry Harrison where he rose to the rank of Captain.

After he was severely wounded at the battle of Tippecanoe, he recuperated from his severe wounds in St. Louis. There he became assistant Indian Agent to his Uncle William Clark of Lewis and Clark Expedition fame, who was then the Indian agent for Missouri and later became Governor of the territory.

John acquired the “Colonel” designation when he was appointed adjutant general of the Missouri State Militia in 1820. He simply promoted himself.

Later John O'Fallon was a contractor, buying and selling supplies to the Army. This proved a profitable business and he accumulated a considerable fortune. He invested his newly acquired wealth in a number of very lucrative enterprises, among them railroads. He was one of the promoters of the Pacific Railroad (now Missouri Pacific) as well as the North Missouri Railroad (now the Wabash) and the Ohio and Mississippi (now Baltimore and Ohio) and was the first president of each of these railroads.   [ Commentary written c. 1954 - ed. ]

His railroad involvement also brought him farther west to the Missouri-Iowa border and along the way resulted in his becoming the namesake of O'Fallon Missouri in 1860.

His most gainful investment was two large tracts of land now part of northern St. Louis, which he subdivided into building lots. On a part of one of these tracts he built a large country home which he named Athlone for the town in Ireland from which his father had come. This estate was later acquired by the city of St. Louis and is now O'Fallon Park.

John O'Fallon is remembered for his many charitable and educational benefactions. Among these were gifts to St. Louis University, Washington University, and particularly a large gift to O'Fallon Polytechnic Institute. This latter institution was the forerunner of the St. Louis high schools and public library.

He also assisted the Episcopal Church of which he was a member and built the Methodist Church at the corner of Fourth Street and Washington Avenue in St. Louis of which is wife was a member.

John O'Fallon died December 17, 1865 at his home, 1125 Washington Avenue, St. Louis, Missouri.