Again my source is the cemetery at Mckeesport named Versailles.Samuel Sinclair is buried with his wife Elizabeth McKee and their son HB Sinclair in lot E35.
Some records suggest he was a surveyor for George Washington like the Myers family.The Myers family is buried in lot 34.
One record says:
"Samuel Sinclair came into the valley by 1786 where he was a ferry operator at the confluence of the Monongahela and the Youghiogheney rivers near present day McKeesport Pennsylvania. Samuel’s son, also Samuel, married Elizabeth McKee, daughter of Robert, founder of McKeesport. Samuel Sr was married to Jane St Clair, the sister of James St Clair. Samuel’s land patent was called, “The Bruce”."
Title: History of Pittsburgh and environs, from prehistoric days to the beginning of the American revolution Vol. 1 / By George Thornton Fleming. Author: Fleming, George Thornton, 1855-1928
PG. 553 “ST. CLAIR was born in Thurso, Caithness, Scotland, in 1734. It may be noted he was the fourth from the land of Bruce to have extended mention in Pittsburgh history - his predecessors, Braddock, Halket and Forbes. ST. CLAIR was the grandson of the EARL of ROSLYN and well born, and well educated at the University of Edinburgh. He studies medicine, but having inherited a fortune from his mother he purchased a commission as ensign in the 60th Regiment of Foot in 1757 and came to America with Admiral Boscowan’s fleet. He served under Amherst at Louisburg in 1758 and with Wolfe at Quebec the next year. He resigned his commission in 1762 and coming to Pennsylvania in 1764 settled in the Ligonier Valley, then in Cumberland county; next Bedford, until 1773, when Westmoreland county was formed, in which this famous valley has remained. ST. CLAIR was an active pioneer in the region, owning much land on which he erected a mill and an imposing residence for the times. He was first made surveyor of the Cumberland county district, next was a justice of the court of quarter sessions and common pleas, a member of the Proprietary Council, and previous to the formation of Westmoreland county a justice of the peace and recorder and clerk of the orphans’ court in Bedford county. In July, 1775, he was made colonel of militia, and in the fall of that year he accompanied as secretary the commissioners that were appointed to treat with the western tribes at Fort Pitt. He took the side of the colonies in the Revolution. He served through the whole war and rose to the rank of major-general. He represented Pennsylvania in the Continental Congress from 1785 to 1787, and was president of that body when it passed the famous ordinance of 1787, by which the Northwest Territory was organized. He was governor of this territory from 1789 to 1802. In 1791 he commanded the expedition against the Miami Indians, which ended so disastrously. He was sick at the time and gave his orders on a litter; but public opinion obliged him to resign his command. He returned to civil life and became a farmer on his Westmoreland county land. After a long and (pg. 554) distinguished public service, it was this good man’s fate to live poor and neglected for many year, and to die from an accident, having been found insensible in the road, evidently having been jolted from a small wagon, as his pony remained near the vehicle. He did not regain consciousness, dying the next day, August 31, 1818, aged eighty-four. His name has been widely commemorated.”
NOTE: ST. CLAIR, other family name SINCLAIR.
What is interesting is the Thronton's were well noted to be related to Meriwether Lewis.