Northeast Italy
While underdeveloped compared to Northwest Italy and contemporary Western European countries at the time of unification in 1861, the average wage of the Two Sicilies was actually higher than Central Italy and on par with Northeast Italy. The island of Sicily, in particular, was richer than the mainland part of the kingdom and its wages were very close to the northwest's. Divergence increased massively after unification however, mostly due to the continuing poor state of human capital in the south throughout the Savoyard rule.