Frost line depth in Van Buren County, MI
How deep the ground freezes in Van Buren County, MI
23 in. Dig to 23 in, just below the frost. Nearest NOAA station: S Haven, 8.3 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.