| 1. ||Illinois-Wisconsin (Winnebago County), Rockford quadrangle : topography ||Rockford (Ill.); Winnebago County (Ill.); Wisconsin; Maps; Topographic maps; Topography; Illinois ||Relief shown by contours and spot heights.; "Surveyed in 1917."; "Surveyed in cooperation with the War Department and the State of Illinois."; "Contour interval 20 feet."