The United States is rich also in forests, despite the prodigal waste of timber that has gone on for more than a century. Oak, pine, cypress, and other kinds of trees are found in abundance, which accounts for the common saying that "America is a land of wooden houses." Every year the forests of the country yield billions of feet of lumber, and enormous quantities of wood pulp, fuel, mine props, and numerous other products of commerce. As might be supposed, our forests are in danger of depletion. The national government, however, as well as a number of the states, have undertaken seriously within the past few years to prevent forest waste and to see that planting of forest trees is not neglected.

Average Value of Land in Farms per Acre, by Counties: 1910.

Average Value of Land in Farms per Acre, by Counties: 1910.

Our mines are also rich, numerous, and widely distributed. The California gold fields were for many years after 1848 the El Dorado of the whole world. This industry is still important, though it has been robbed of much of its romance and glamour by the more prosy methods of capitalistic production. Soft coal is found in abundance in many widely separated regions, while hard-coal mining is confined to eastern Pennsylvania. Our deposits of iron ore, which seem to be almost inexhaustible, are also found in many localities. Silver, copper, zinc, and lead add materially to our mineral resources, while petroleum, from which gasoline, oils, and other products of commerce are made, mounts annually in value to hundreds of millions of dollars.