Frost line depth in Freeborn County, MN
How deep the ground freezes in Freeborn County, MN
50 in. Dig to 51 in, just below the frost. Nearest NOAA station: Albert Lea 3se, 5.3 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.