The acre was used to subdivide up square miles. It makes more sense if you know 43,650 = 660 * 66. Also, 660 feet is exactly 1/8 of a mile. So once a square mile had been surveyed, you could split each side in half to get 4 squares of 160 acres. You could then split each of those again to get 40 acres (hence the “40 acres and a mule”), and then you could split them again to get 10-acre squares. Then you could split them into 5-acre rectangles, etc. The rectangles are good at keeping access to an existing road, although the skinniness isn’t great. And all of these sub-divisions could live on the same grid.
The acre was used to subdivide up square miles. It makes more sense if you know 43,650 = 660 * 66. Also, 660 feet is exactly 1/8 of a mile. So once a square mile had been surveyed, you could split each side in half to get 4 squares of 160 acres. You could then split each of those again to get 40 acres (hence the “40 acres and a mule”), and then you could split them again to get 10-acre squares. Then you could split them into 5-acre rectangles, etc. The rectangles are good at keeping access to an existing road, although the skinniness isn’t great. And all of these sub-divisions could live on the same grid.