The main subdivision of the grid was the ‘township’ – a 6-mile by 6-mile square (the decimally minded Jefferson had argued for 10 by 10) that contained thirty-six subdivisions of a square mile each.23 The base unit of measurement would be Gunter’s chain, 66 feet long, with its subdivisions of a hundred links. As a square mile contained 640 acres, the chain was a perfect unit for division, with each 40-acre plot (the smallest area of land that could be purchased) measured out in 20 chains’ length.
