Change in grid along Thirty-first street.
Although the Chicago area was surveyed and marked off into legal "squares" in 1821, the tilted angle of most Bridgeport streets north of Thirty-first street are oriented with reference to Archer avenue. The reason being was that Archer Road had been built before any of the north-south/east-west grid streets were real. In other words, the rectangular survey was a plan not yet fully implemented. The principles of the rectangular survey were evident nonetheless. Cross-streets are set out at right-angles (the meaning of the word rectangle) to Archer Road, but only as far as the section line which later became Thirty-first street. Note that the white house in the left of the photograph was originally a rectangular building and later extended to fill in the space up to the sidewalk/street. This was much the way Bridgeport itself had grown.