ants, cattle diseases, and insect pests.

_Chicago_ is the largest food-market in the world. The industries of the
city are almost wholly connected with the commerce of grain, pork, meat,
and other food-stuffs. For the transportation of these commodities about
thirty great trunk lines enter the city and about twelve hundred
passenger trains daily arrive and depart from its stations.

The freight terminals are connected by transfer and belt lines, which
receive and distribute the cars passing between the eastern and the
western roads. More than five hundred freight trains, aggregating about
twenty thousand cars, arrive and depart daily.

_St. Louis_ originally derived its importance as a river-port of the
Mississippi, having been the connecting commercial link between the
upper and the lower river. In recent years it has become the metropolis
of the southern part of the food-producing region. In addition to the
river-trade, still largely controlled at this point, it is the focus of
more than twenty trunk lines of railway. Some of these, like the trunk
lines of Chicago, handle freight exchanged between the East and West;
but a large proportion are receiving and distributing roads for Southern
freight.

[Illustration: AUTOMOTIVE POWER IN THE INDUSTRIES OF THE MISSISSIPPI
VALLEY]

_St. Paul_ and _Minneapolis_ are the metropolis of the upper
Mississippi. The former grew from a trading-post at the head of
navigation; the latter gained its commercial prominence from the
water-power at the falls of St. Anthony. The former has become the chief
railway and distributing centre of the northern Mississippi Valley; the
latter has the greatest flour-mills in the world, and an extensive
lumber-trade. Both are situated on the trade-route between the United
States and Asian ports, and distribute a part of the trade that comes
from them.

The two _Kansas Cities_,[52] _Omaha_, _South Omaha_, and _Sioux City_
are stock-markets and meat-packing centres. The first two named are
collecting and distributing points not only for the Mississippi Valley,
but also for a considerable share of the Pacific Coast trade. Kansas
City is also a transfer station for the cotton destined for China. From
this place it is sent by way of Billings to Seattle, and thence shipped
to China.

_Cincinnati_ is the metropolis of the Ohio Valley. Its situation on a
bend of the river gives most excellent landing facilities; the easy
grade from the bluff to the bo