Frost line depth in Ingham County, MI
How deep the ground freezes in Ingham County, MI
31 in. Dig to 32 in, just below the frost. Nearest NOAA station: East Lansing 4 S, 7.5 mi.
Your building department sets the legal frost line depth (IRC Table R301.2(1)); footings must go below it (R403.1.4.1). Call them before you dig.