Answer:
The Northeast.
Step-by-step explanation:
In the northeastern US is the largest and oldest industrial concentration in the country, the so-called manufacturing belt. The resources and sources of energy are: iron ore, steel, petrochemical, textile, aeronautics, aerospace and technopolies.
This industrialization made this region the richest part of the country, where people had a better quality of life. Because of all this quality this region was the most associated with educated workers, unionized and high land costs.