Frost line depth in Alcona County, MI
How deep the ground freezes in Alcona County, MI
44 in. Dig to 44 in, just below the frost. Nearest NOAA station: Harrisville 2nne, 1.8 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.