Corners and curvature

When I lived in Ohio, I noticed certain spots where long, straight roads would abruptly turn right or left in a sharp corner, jog a short distance to the side, then angle back in the original direction. I called those "screw you corners" because I imagined they were the result of an obstinate land owner saying "screw you" when The Man came to buy up some land for a road. 

Turns out that some of these were probably the result of necessary corrections for the curvature of the earth

“It did not take long for legislators to understand that a township could not be exactly six miles on each side if the north-south lines were to follow the lines of longitude, which converged, or narrowed, to the north," explains landscape architect James Corner in Taking Measures Across the American Landscape. "The grid was, therefore, corrected every four townships to maintain equal allocations of land.” 

Author Kurt Mein, in his book Correction Lines, treats this kind of distortion as an example of how an ideal plan must incorporate imperfection in order to be implemented in an imperfect world.