Commerce has been aptly defined as "taking things from where they are plentiful to where they are needed." This being true, the volume of internal commerce of any country must depend upon the number of its people, the total volume of its production, the sectional diversity of its products, the efficiency and cheapness of its transportation, and the freedom from foreign competition in the sale of native commodities in home markets. In the economic progress of the United States from 1860 to 1900, there was a continuous and rapid development of all the requisite factors for the existence of a large internal trade. Population more than doubled, annual production per capita quadrupled, the diversification of industry became more pronounced and the transportation system developed to a degree that afforded the utmost fluidity of movement of all articles of trade. Furthermore, the range of movement of internal trade was greatly widened by the settlement of the vast expanse of new country west of the Mississippi River. The extent, volume and complexity of internal trade during this period render it impossible to attempt, within the scope of this paper, to give a connected account of its development. However, some idea of its wonderful expansion may be conveyed by the following brief statement of the growth of the movement of some of the most important commodities. _Cereals and Flour._ The history of the internal grain trade from 1860 to 1900 centers around the receipts and shipments at the great primary grain markets situated on the Great Lakes and the rivers of the upper Mississippi Valley. In 1900 the chief surplus cereal area of the United States comprised a vast stretch of territory included in a semicircle described by a southern and western sweep of a compass moving on a radius extending from Duluth to Buffalo. Three-fourths of the 4,500,000,000 bushels of grain were raised in the twelve states embraced in this territory. The ten most important markets in the region, each of which was receiving annually from 10,000,000 to 300,000,000 bushels of grain, were Chicago, Minneapolis, Duluth-Superior, St. Louis, Milwaukee, Toledo, Kansas City, Peoria, Cincinnati and Detroit. From each of these points there radiated toward the South and West a network of railways over which grain came from the farming districts and over some of which there was a return movement of flour and grain for domestic consumption or for exportation from Gulf ports, while stretching to the eastward were numerous rail and water lines by which an immense cereal and flour traffic was carried to the manufacturing districts and exporting cities of the Atlantic coast. In 1900 the ten markets named received about 850,000,000 bushels of grain, including flour, and shipped 650,000,000 bushels.