| 1. |  | Illinois (Warren County), Monmouth quadrangle | Monmouth (Ill.); Warren County (Ill.); Illinois; Maps; Topographic maps; Topography | 1 map : col.; "Contour interval 20 feet."; "Surveyed in 1920-1921."; "Surveyed in cooperation with the State of Illinois." Coordinates: (W 90⁰45ʹ00ʺ--W 90⁰30ʹ00ʺ/N 41⁰00ʹ00ʺ--N 40⁰45ʹ00ʺ)... |
