Think about what you've learned about the role of railroads in make resources available. check all of the statements that are true. railroads created less demand for raw materials. railroads americans access new sources of raw materials. new cities grew into manufacturing centers that refined natural resources. trains required more materials to run and to be built, industries grow. a map of the united notes showing the industrial centers of the country at the end of the nineteenth century shaded green. some cities labeled within these green sections are boston, new york, pittsburgh, cleveland, birmingham, saint paul, saint louis, kansas city, denver, and san francisco.