The Old Seven Ranges was the first tract of land surveyed by the federal government under the PLSS. The Old Seven Ranges tract is approximately 3,000 square miles, and encompasses all or part of the modern day Ohio counties of: Monroe, Harrison, Belmont, Jefferson, Carroll, Columbiana, Tuscarawas, Guernsey, Noble, and Washington. To divide the tract, a Geographer's Line (or a base line) was run due west from the point in which the southwestern corner of Pennsylvania meets the Ohio River, and extended thenceforth for 42 miles. All territory falling south of this line to the Ohio River is within the Old Seven Ranges tract. The Geographer's Line is also known as Ellicott's Line after the namesake of Andrew Ellicott who surveyed the line in 1785.
From the Geographer's Line, lines denoting ranges were run south from a point every 6 miles with markers or monuments being placed every 12 miles until there were seven ranges of townships being 6-miles-wide increasing west from the Pennsylvania border. Survey townships were counted up from the Ohio River base to the Geographer's Line. Due to the meandering of the Ohio River, township numbering appears to have a "stairstep" pattern where adjacent townships do not share the same number designation. In the viewer above, you can see that townships just south of the Geographer's Line are denoted as 9N 2W, 12N 3W, 13N 4W, 14N 5W, 15N 6W, and 16N 7W. None of these adjacent townships share the same number designation. In modern cadastral surveys, a base line serves as the axis from which townships are numbered either to the north or south; increasing in number as they get further away from the base line. Fractional townships exist where the Ohio River meanders through and along the perimeter of the tract. Townships in Range 1 West are entirely fractional.
East-west lines separating townships on their north-south sides were not marked or monumented on the grounds by surveyors as an economical measure taken by the federal government (surveyors were paid by the mile). Rather, east-west lines were only marked on survey plats which led to distortion of the boundary lines as they physically appeared on the ground. Many settlers found that township corners did not line up when they showed up to survey the property they had just acquired from the federal government. For an example of the distortion of township corners see the intersection of townships 10N 3W, 11N 3W, 11N 4W, and 12N 4W in the viewer above. In the Act of February 11, 1805, Congress legally fixed and made unchangeable all township corners certified by the Surveyor General regardless of whether the corners were initially set erroneously.