What was the main reason the us civil war started?

A common explanation is that the Civil War was fought over the moral issue of slavery. In fact, it was the economics of slavery and political control of that system that was central to the conflict

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.

i would go with the last one