Well, there more then one frost line in Illinois: 1) 10" to 20" for Southern Illinois 2) 15" to 30" for Central Illinois (frost line for Peoria) 3) 20" to 35" for Northern Illinois
3 feet 6 inches
no Frost
I saw a good chart of average frost penetration for Illinois. 10" to 20" for southern Illinois 15" to 30" for central Illinois (frost line for Peoria) 20" to 35" for northern Illinois
no Frost
one metre
42"
42 inches
3ft
What is the frost line depth in louisville Kentucky
48"
the frost line is 36"