The five states of the Northern Plains -- Wyoming, Montana, North Dakota, South Dakota and Nebraska -- offer a vivid lesson in the history of America's westward expansion, as well as some of the country's most spectacular scenery.

Of special interest are the six national parks within the plains states: Yellowstone, Grand Teton, Glacier, Theodore Roosevelt, Badlands and Wind Cave. Less familiar, but well worth visiting, are a number of other national monuments and historic sites, among them: Grant-Kohrs Ranch National Historic Site, Montana: Once a prosperous cattle ranch, and one of the first in Montana in the 1850s, it has been preserved to illustrate the development of the Northern Plains cattle industry. Cattle are still raised here. Devils Tower National Monument, Wyoming: A volcanic formation, the dramatic rock tower rises 865 feet from a pine-covered hill on the edge of the plains. It was America's first national monument, created in 1906. A mile-long trail circles the base. Fort Union Trading Post National Historic Site, North Dakota: From 1829 to 1867, the Missouri River fort was a major fur-trading depot. Only the foundations remain now, but archeological digs are ongoing, and the fort's palisades and other structures are expected to be reconstructed in the next few years. Agate Fossil Beds National Monument, Nebraska: Exploratory digs continue daily in the summer for the bones of dinosaurs deposited in two mounds beside the Niobrara River. A two-mile round-trip trail leads to the site, where a ranger explains the archeological work. Fort Laramie National Historic Site, Wyoming: Built to protect the '49er wagon trains on the Oregon Trail, this large fort on the North Platte and Laramie rivers was a major supply point of men and materials in the Indian wars of the 1870s and 1880s. Knife River Indian Villages National Historic Site, North Dakota: For hundreds of years, Indians made their village where the Knife River joins the Missouri. Thousands of remnants of the Plains Indian have been dug from the park site, and many are displayed.