| 1. |  | Hillsboro quadrangle, Illinois : 15 minute series (topographic) | Illinois; Maps; Topographic maps; Topography; Hillsboro (Ill.) | 1 map : col.; Relief shown by contours and spot heights.; Contour interval 20 feet.; "Culture and drainage in part compiled from aerial photographs taken 1938. Topography by plane-table methods 1947." |
