John Blair was born in 1687 in Scotland, the son of Archibald Blair, brother of James Blair. His father was a student at the University of Edinburgh in 1685; he married three times, and John Blair was the son of the first wife, whose name is unknown.
John received his education at the College of William and Mary.
As early as 1713 Blair held the position of deputy auditor-general pro tem. His uncle and father were both prominent in the political affairs of the colony, and he doubtless owed much to their influence. His father was a member of the House of Burgesses, 1718-1734. On February 5, 1727, John Blair was appointed naval officer for the upper district of James River, and on August 15, 1728, he took oath as deputy auditor-general, which position he filled until his death in 1771. From 1734 to 1740 he was a member of the House of Burgesses. According to Gooch, Blair was in narrow circumstances until he and his children received about $810, 000 by the will of his uncle James Blair, who died in 1743.
On February 26, 1745, Gooch recommended John Blair for appointment to the Council and this recommendation was approved by the board of trade. Among Blair's activities was an interest in lands in the western part of the colony. As early as November 4, 1745, a grant to him and his associates of 100, 000 acres west of the Fairfax line was voted by the council. In addition to his services as councillor, Blair was appointed in 1746 on the committee to revise the laws, and was one of the committee of correspondence with the colonial agent Montague in England. As president of the Council he was twice called upon to act as governor, from January 1758, the time of Dinwiddie's departure, until the arrival of Fauquier, June 7, 1758; and again from Fauquier's death, March 3, 1768, to the arrival of Botetourt in October 1768.
As governor, he seems to have been agreeable to all political factions. His letter to the King's attorney of Spotsylvania County, July 16, 1768, in regard to the treatment of Baptists, gives us a most favorable view of his character. Instead of countenancing persecution of this sect, he advocated a liberal and sympathetic policy. In the Two Penny Act controversy he took the popular view and supported the act by his vote in council. He fully approved of the doctrine expressed by the General Assembly March 31, 1768, that only the Assembly could make laws regarding the colony's internal policy of taxation. When Gov. Botetourt died October 15, 1770, the duties of governor would again have devolved upon Blair but in order to avoid this, he resigned his seat in the Council. His death occurred in his eighty-fifth year.
John Blair was an honorable man and well-known politician of his time. He sat on the governor's Council (1745–1770), becoming its president in 1757 and serving as acting governor on four occasions. He served as York County justice of the peace (1724–1745) and a burgess from Williamsburg from 1736 to 1740. He also joined the House of Burgesses representing Jamestown (1724–1736).
Blair was married to Mary Munro, daughter of Rev. John and Christian Monro, of St. Johns Parish, King William County, by whom he had ten children.
