McCullough's Trading Path originated in game trails that early Indian Traders found useful in crossing from the Valley of Virginia, westward and then north into the Monongahela and Ohio River Valley's. Georgia Washington, in a futile quest to find a suitable road through the Virginia Highlands to the Ohio, traveled eastward on McCullogh's Trading path in the fall of 1784, He described it's origins this way
McCullocks path...owes its origen to Buffaloes, being no other than their tracks from one lick to another & consequently crooked & not well chosen.
But MucCullough's Trading Path had been traveled by Europeans since at least 1736 when William Mayo is believed to have used it to reach the headwaters of the Potomic, as the head of an eight man surveying party sent out by Lord Fairfax to establsh the western boundary of his grant. By 1747 the trail was being used extensively by Indian Traders to reach the Ohio.
As early as 1747 no fewer than three hundred traders reached the Ohio; and the next year one caravan of seventy horses, loaded with furs, made the journey from the Scioto River to Philadelphia. These traders followed two general trails westward from Winchester: the one passing by the site of Cumberland to Pittsburg; the other ascending the Potomac to its source and crossing to the Greenbrier and thence to the Kanawha.
One of the traders that made use of the "southern route" accessing the Ohio country, was John McCullough, for whom McCullough Trading Path came to be known. McCullough, his family, and his wife's family, the Inskips, had come to the South Branch after 1752, settling at Old Fields. Rather than farm, McCullough took to trading, to which end he establish a camp on the Monongahela "between the mouth of the Cheat River, and Neals Ferry". The exact location of this camp is not clear, but it was probably near the modern community of New Geneva at the mouth of Georges Creek, in Southwestern Pennsylvania. During the French and Indian War he provided oats and Indian Corn for forage to the military wagon trains that passed up the South Branch. George Washington employed him as his wagon master when traveling from Pearsals Fort on the lower South Branch to Fort Cumberland in Pennsylvania. Washington would recommend him to Henry Bouquet, second in command of Forbes Expedition of 1758 as someone “who woud make an exceeding good Waggon Master.”
The McCullough family moved to the Ohio Valley circa 1772..”, settling near Pittsburg where he became prominent in local affairs. This relocation may not have been entirely voluntary. one historian of the area writes
He was in the habit of supplying the Indians, even in times of war, with knives, hatchets, powder, &c. The settlers complained of this, and threatened him, but he would not desist. At length they determined to enforce their threats. Learning that he sometimes returned by Sandy Creek and Braddock's road, a number of the settlers from about the Great Crossings and Turkey Foot, disguised themselves, and went in pursuit. They caught him at Jesse Tomlinson's, at the Little Crossings, or Castleman's river. They gave him to know that his contraband trade must cease. Mac. resisted and threatened and entreated. Tomlinson, it is said, sought to protect him as his guest. But the men were in earnest. Tom Fossit was one of them. Tom caught and held him in his giant grasp, while others, as the term used was, "deviled him," until he promised never more to transgress. After despoiling him of his ill gotten peltry and other pelf, they let him go, and he never was seen again in this region of country.
The above story may be fanciful, as "Old Tom Fossitt" referenced above is also said to have claimed to have been the one who killed Gen. Edward Braddock during the Braddocks ill-fated campaign against the French in 1756. In any case, McCullough and his family were certainly in the Pittsburgh area shortly before the Revolution,
John McCullough served in the court along with other noted early settlers George Croghan, Edward Ward, Thomas Smallman, John Gibson, Dorsey Pentecost, John Campbell, John Canon, David Shepherd and William Crawford. In 1775 at a "meeting of the inhabitants of that part of Augusta County that lies on the west side of the Laurel Hill, at Pittsburgh, the 16th of May, 1775" this same John McCullough joined many of the above named men in a proclamation opposing British tyranny. These Articles of Association lead to the formation of militia to aid the Continental Congress in fighting the Revolution....On September 17, 1776 John McColloch was named a Gentleman Justice with Edward Ward, Dorsey Pentecost, John Canon and David Shepherd for the newly formed VA county of Yohogania. In 1777 John McColloch was sworn as High Sherriff of Ohio Co., VA at Black's cabin.
We can infer from this that despite any concerns about his trade with the INdians, McCullough was a well respected and influential person in the community. McCullough died shortly after he was sworn in as HIgh Sheriff. He is said to have been visiting one of his sons on Short Creek in WV, and returning home died of either cholera or yellow fever in Pittsburgh.