How did the growth of the railroads affect supply and demand for natural resources in the United St The growth of the railroads decreased the supply of natural resources.
The growth of the railroads decreased the demand for natural resources.
The growth of the railroads increased the demand for natural resources.
The growth of the railroads had no effect on the supply of natural resources.

Rail road construction crews were not only subjected to extreme weather conditions, they had to lay tracks across and through many natural geographic features

worldwide, 780 million people do not have access to an improved water source. an estimated 2.5 billion people lack access to improved sanitation (more than 35% of the world's population)

food chain i would say only because there is competition on getting food and survival