ates. Broad general
principles of conservation applicable to the North American continent
were adopted.

[Illustration: Portrait]
Gifford Pinchot, President
of the Conservation Commission.

The movement was materially strengthened also through the withdrawal of
large areas of the public domain from private entry. Thus 148,000,000
acres of forests and 80,000,000 acres of coal land were withdrawn during
President Roosevelt's administrations.

Directly connected with the problems of conservation are those of
irrigation. The so-called arid regions constitute two-fifths of the
area of the United States, or some 1,200,000 square miles. Of this vast
region, it has been estimated that about one-tenth can be irrigated to
advantage. By the end of the year 1908, some 13,000,000 acres had been
reclaimed, or nearly one-third of the total amount suitable for
irrigation purposes. This has brought about the rapid growth of cities
and a substantial industrial advance in the former arid regions of the
far West. The most notable impulse to this movement was made in 1902
when Congress passed a law, the Reclamation act, providing that the
proceeds from the sales of public lands in thirteen States and three
Territories should be expended by the National Government in the
construction of irrigation works.

The total receipts from the sales of these lands amounted to $28,000,000
by the end of the year 1905, and twenty-three projects, dams,
reservoirs, or canals were in different stages of construction. The most
important of these undertakings were the Roosevelt Dam, the Shoshone
Dam, and the Truckee-Carson Canal.

[Illustration]
Built by the U. S. Reclamation Service.
Roosevelt Dam from the road.

The Roosevelt Dam is the chief work of construction in what is called
the Salt River project. By the completion of this work at least 200,000
acres in the vicinity of Phoenix, Arizona, were reclaimed. This dam is
284 feet high, 1,080 feet long on the crest, and 165 feet thick at the
base. The resulting reservoir with a storage area of 16,320 acres will
be the largest artificially formed lake in the world. It forms a body
of water 25 miles long, almost 2 miles broad, and with a maximum depth
of 220 feet. The main canals are 119 miles in length and the lateral
canals 208 miles. Not only will this structure insure a supply of water
in the Salt River valley where, in recent years, orchards and other
products have perished, but it will