Try your local AAA (Automobile Association of America) office. You might have to pay a small fee for it if you are not a member. If you live in Idaho, your local Chamber of Commerce may have something like that.I don t think you want 1 mile = 1 mile scale unless you want your map to be as big as the state of Idaho.
USGS 15 minute-series topographical contour maps work out to about 1 =1mile