Spreading north the frontiersmen had reached the Rappahannock and the Potomac by 1650, and settlers began moving into Lancaster County. In 1653 the first settlers established themselves in what is now King William County. Just before the end of the seventeenth century the tobacco industry had expanded into the lowlands all along the Rappahannock and Potomac rivers below the Fall Line. In 1689 the York River area produced the largest quantity of tobacco, the Rappahannock River area was second, the Upper James third, and the Accomac Peninsula last. While the production of tobacco continued to expand north and west, it made little headway in the sandy counties of Princess Anne and Norfolk. All during the seventeenth century expansion tended to extend in a northerly direction within the Tidewater region, but in the eighteenth century the movement was to the west in search of virgin soil. Planters began moving beyond the Fall Line soon after the turn of the century. Robert Carter of Nomini Hall patented over 900 acres of land above the Falls in 1707. It is generally agreed that the commercial production of tobacco began to expand beyond the Fall Line about 1720. In 1723 a traveler, who had just visited above the Falls, mentioned seeing many fields of tobacco. In the following year Robert Carter had hundreds of additional acres surveyed, in what is now Prince William County, as he extended his holdings above the Fall Line. The tobacco industry seems to have been fairly well established as far west as Spotsylvania, Hanover, and Goochland counties as early as 1730. In the year 1740 Elias and William Edmunds were among the first settlers in Fauquier County. They settled near what is now Warrenton and began producing tobacco of excellent quality, which soon came to be known as "Edmonium Tobacco." Ten years later large quantities were being produced in Albemarle (including present Nelson and Amherst counties), Cumberland, Augusta, and Culpeper counties. During the six-year period 1750-1755, tobacco production appears to have been centered equally in three areas: the Upper James River district, the York River district, and the Rappahannock River district. Each of the three districts exported about 83,000 hogsheads of tobacco, while the Lower James River district exported only about 10,000. Just prior to the American Revolution the tobacco industry began to expand rapidly south of the James River, especially to the south and west of Petersburg. One observer declared in 1769 that the Petersburg warehouses contained more tobacco than all the rest of the warehouses on the James or the York River. It was estimated that 20,000 hogsheads were being produced annually in that region alone. A considerable amount of tobacco was also being grown in the lower region of the Valley of Virginia.