Facets of the geography of population in the midwest

Americans seem to be moving constantly, and they always have been. They moved to the frontier from the older settled areas in the East, and they were joined by immigrants from Europe once railroads had been constructed. They moved from the farms to the central places that served them. They moved from the central city to its suburbs, and now they are moving to the exurbs. They are moving to distant amenity areas when they.retire. To a considerable degree, the various streams of movement are independent one from another. Their strength has varied with time. Quite often one has been waxing while another has been waning, and on occasion they have even managed to cancel each other out, but you cannot hope to understand the patterns and growth of population in the US without a clear sense of the variations in its major components.