Scale 1:500,000. 1 in. equals approximately 8 miles ; Lambert conformal conic projection, based on standard parallels 33° and 45° (W 92°53ʹ--W 86°34ʹ/N 47°18ʹ--N 42°29ʹ).
Note
Relief shown by contours and spot heights. Source data: Geological Survey topographic maps, Corps of Engineers topographic maps. "Compiled in 1966." "Highways corrected to 1967." Includes "Population key."