These railroads include an enormous aggregate of works and structures in the form of tunnels, cuts, banks, bridges, stations, and shops.
There are in the country (1914) about 2,228,000 miles of public roads, of which 10 per cent are "surfaced" roads.

No figures are now available of the number of wagons, horses, automobiles, and other vehicles in use on the roads and streets for purposes of transportation.
Many of our economic problems are presented by these transportation agencies, from the question of opening a new dirt road in a rural township to that of building an inter-oceanic canal, from the question whether to have free public roads or toll roads to that of regulating the railroad rates on the whole railroad system of the country.
Sec.11.

#Raw materials for clothing, shelter, machinery, etc.# The farm lands supply, besides food, a large part of the raw materials for many other goods, such materials as cotton, flax, wool, hides, feathers, lumber, and firewood.

The farm woodlots compose about 200,000,000 acres, and the large forests, public and private, about 350,000,000 acres, a total of about one-fourth the area of the country in forests, containing about one-half of the lumber that the country once possessed.

The economic problem of a sound forestry policy is one of the largest we have to solve.
The most important other sources of raw materials for industry are the mineral deposits in the earth's surface.[8] This country is stored more bountifully, probably, than is any other country, with the metal ores of iron, copper, lead, zinc, gold, and silver.