As the United States converted dirt roads into paved roads?

the indians crossed artificial boundaries, setting the stage for conflict

most people now work in jobs where they do one  kind  of work; they are carpenters, bankers, cooks, mechanics, and so forth. likewise, most  businesses produce  only certainkinds  of  goods  or  services, such as cars, tacos, or gardening  services. this feature of  production  is known as specialization.