What are the two biggest reasons that Rome was in the center of the Empire?

Constantinople was the largest and richest urban center in the Eastern Mediterranean Sea during the late Eastern Roman Empire, mostly as a result of its strategic position commanding the trade routes between the Aegean Sea and the Black Sea. It would remain the capital of the eastern, Greek-speaking empire for over a thousand years.

workers of lowell mills were greatly benefited for the waltham type of work which was more a paternalist kind, trying to protect the integrity of this little girls coming from small farmers and providing an adequate place of work, this in an effort to avoid the issues of bad place conditions and immorality that the people in bigger industrialized cities of great britain were experimenting.

b.   jim crow laws were enacted in northern states.