The reason for this long pause between the first and last acts in the story of the Great West is found in the fact that later exploration soon determined in favor of the Platte Valley, as the one affording by far the shortest way through the centre of the continent. Therefore the new States, just named, are mostly an outgrowth of the more central region in which the great body of emigration has first settled. It may be further remarked, that in those Territories where gold and silver occur, settlement was nearly simultaneous. IDAHO,[1] like Nevada, grew up from the discovery of gold and silver in her borders. The finding of these precious metals goes no farther back than the summer of 1862. These were placer deposits. A year later quartz lodes, rivalling in richness those of Colorado, were brought to light. Soon the old Hudson's Bay post of Fort Boisé[2] was turned into a thrifty town. The mineral find rapidly extended along the Salmon, Boisé, and Clearwater Rivers. In the south, Idaho City sprung up on the Boisé; in the north, Lewiston on the Clearwater was settled. In 1860 Idaho scarcely had any white people: in 1863 they were sufficiently numerous to entitle them to have a Territorial government. WASHINGTON[3] is another rib taken from the side of the older Oregon, whose boundaries so fortunately gave us the magnificent harbors embraced by Puget Sound. Here therefore is the natural terminus of the Northern Pacific Railway,[4] which comes from Duluth and St. Paul, crosses the tier of States now under consideration, and reaches Tacoma by way of the Lower Columbia. Washington was made a State in 1889. MONTANA.[5] About all known of this Territory in 1860 was that it contained two important military posts: Fort Benton at the head of navigation on the Missouri, and Fort Union near the mouth of the Yellowstone. But in 1861 gold was found in a gulch lying at the head of the Jefferson Fork of the Missouri. Population rushed in. Here Bannack City was founded. As with Colorado and Nevada, so here the surface diggings were quickly worked out. In 1862 Virginia City was founded as the successor of Bannack; and in 1863 Helena as the successor of Virginia, and supply-point for the mines of the Blackfeet country. Montana was organized as a Territory in 1864. A year later there were but four post-offices, at which tri-weekly mails were received, while but one newspaper was printed in the Territory. Yet even at this early day, when mining engrossed the attention of nine-tenths of the population, it was seen that the agricultural resources of Montana were very great, and since the building of the Northern Pacific Railway along the Yellowstone, that valley has become to Montana what the Willamette is to Oregon. Montana was admitted to the Union in 1889.