Frost line depth in Lincoln County, MN
How deep the ground freezes in Lincoln County, MN
58 in. Dig to 58 in, just below the frost. Nearest NOAA station: Astoria 4s, 14.4 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.