Frost line depth in Person County, NC
How deep the ground freezes in Person County, NC
12 in. Dig to 12 in, the 12 in code minimum. Nearest NOAA station: Roxboro 7 Ese, 5.7 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.