because of the colored population, but because of the darkness of the
soil. Since this land has always been prosperous, it has regularly been
conservative in politics.

The Atlantic coastal plain is by no means the only part of the United
States where the fertility of the soil is the dominant fact in the life
of the people. Because of their rich soil the prairies which extend from
western Ohio to the Missouri River and northward into Canada are fast
becoming the most steadily prosperous part of America. They owe their
surpassing richness largely to glaciation. We have already seen how the
coming of the ice-sheet benefited the regions on the borders of the old
Laurentian highland. This same benefit extended over practically the
whole of what are now the prairies. Before the advent of the ice the
whole section consisted of a broadly banded coastal plain much older
than that of the Atlantic coast. When the ice with its burden of
material scraped from the hills of the north passed over the coastal
plain, it filled the hollows with rich new soil. The icy streams that
flowed out from the glaciers were full of fine sediment, which they
deposited over enormous flood plains. During dry seasons the winds
picked up this dust and spread it out still more widely, forming the
great banks of yellow loess whose fertile soil mantles the sides of many
a valley in the Mississippi basin. Thus glaciers, streams, and winds
laid down ten, twenty, fifty, or even one hundred feet of the finest,
most fertile soil. We have already seen how much the soil was improved
by glaciation in Wisconsin and Ohio. It was in the prairie States that
this improvement reached a maximum. The soil there is not only fine
grained and free from rocks, but it consists of particles brought from
widely different sources and is therefore full of all kinds of plant
foods. In most parts of the world a fine-grained soil is formed only
after a prolonged period of weathering which leaches out many valuable
chemical elements. In the prairies, however, the soil consists largely
of materials that were mechanically ground to dust by the ice without
being exposed to the action of weathering. Thus they have reached their
present resting-places without the loss of any of their original plant
foods. When such a soil is found with a climate which is good for crops
and which is also highly stimulating to man, the combination is almost
ideal. There is some justification for those who sa