It helped because one, farmers could only produce what they needed and enough to sell to the *nearby* people. With railroads, transportation was super duper cheap and maximum fast. And two, it also changed communications, although the telegraph did that more, and it made the country a country that could be crossed in a matter of days, not months, so much smaller in a way. And three, the railroads even helped shape the physical growth of cities and towns, as steam railroads and then electric street railways facilitated growth along their lines and made suburban living feasible.
