Forest growth in Wyoming is limited to the highest mountain ranges, the most important forests being in the Black Hills region in the N.E., on the lower slopes of the Bighorn Mountains, and in the Rocky Mountain ranges of the N.W.
Under the Reclamation Act passed by Congress in 1902 the irrigation of 10o,000 acres in the Belle Fourche Valley adjacent to the Black Hills region was provided for.
This included, roughly speaking, all of the land between the Missouri River and the Black Hills and between the White River and the Big Cheyenne and a strip extending north from the Black Hills to the North Dakota line between the 102nd and 103rd meridians.
The area irrigated by streams was confined largely to the Black Hills region, the water being supplied by the North Fork and the South Fork Rivers, which are tributaries of the Cheyenne.
The minerals of South Dakota, of which gold is the most important, are chiefly found in the Black Hills region.
The larger valleys of the Black Hills district contain fertile alluvial deposits washed from the neighbouring highlands, but in the plains adjoining these mountains the soils consist of a stiff gumbo suitable only for pasture land.
Of the Territory, as has been already said, had been set apart (1868) as a hunting ground for the Sioux Indians, but the rumour of the discovery of gold in the Black Hills and the Bighorn Mountains in1874-1875caused a rush to the region which the military seemed powerless to prevent.