Out of the frontier have come many familiar historical figures and characters who have stood tall in American popular culture. In the Appalachian woodlands there were Daniel Boone, Davy Crockett, and other buckskin-clad, bear-hunting settlers standing beside their log cabins with their Kentucky long rifles. From farther west come images of pioneer families piling into wagons to take the arduous journey over plains, deserts, and mountains in search of new lives on the Pacific coast, while others built sod houses and planted the open prairies with corn. In this varied iconography, railroad crews labor mightily laying track joined with a golden spike; on the plains and in the Southwest mounted native warriors fight courageously but in vain to defend their homelands; in cattle towns steely-eyed gunfighters face one another in the street at high noon; and in the surrounding countryside the most familiar frontier figure of all, the cowboy, watches over his herds, rides the range, and upholds his code of honor against assorted villains.

These images and characters have taken hold in the national imagination partly because they express values that many Americans hold dear. Frontier themes flourish in popular culture because the public seems to need to believe them. But cowboys and overlanders, woodsmen and sodbusters were also part of the frontier of reality - an experience that often demanded true heroism, dogged determination, self-reliance, inventive skills, herculean labors, and many of the other virtues celebrated in the popular view of pioneers.

The frontier's portrayal in popular culture, however, usually overlooks some of its other significance. Westward expansion was a showcase for several of the continent's most important developments in the 18th and 19th centuries. Nowhere was the impact of technological innovation more dramatic. Early in the 19th century, for instance, the invention of the cotton gin propelled the frontier rapidly into the deep South by suddenly making it one of the most economically desirable areas of the world. During the same period steamboats, new road-building techniques, and canal construction similarly stimulated expansion into both the Ohio and the Mississippi valleys.

The technological wonder of the age, the railroad, opened much of the West to invaders from the eastern states and triggered sweeping changes. Generously financed by the national government, transcontinental railroads - first the Union Pacific-Central Pacific and later the Southern Pacific, Northern Pacific, and Great Northern - soon were linked to smaller, "feeder" lines to create a web of rails that opened much of the western interior to outside influences and sped the country's transformation.

Farmers and cattlemen relied on the new technology of barbed wire and windmills to fence fields and pastures on the treeless plains and to pump water for cattle and gardens. New steel-tipped plows allowed homesteaders to slice through prairie soil thick with grass roots. Innovative designs of balloon-frame houses (and by the early 20th century prefabricated houses ordered by mail and delivered by rail), mass-produced stoves, and such products of modern technology as early phonograph players and inexpensive parlor organs eased the difficulties of moving into new country.

The mining frontier was both a product of and contributor to this technological revolution. Without railroads and newer machinery and blasting powder, mining, especially the "hard rock" variety in granite and quartz formations, would not have been possible. Discovery of dazzling lodes of gold and silver and massive deposits of copper in turn inspired new developments in these mining regions. In Colorado major breakthroughs were made in the smelting of ores. More powerful pneumatic drills appeared to speed the work. When rich silver veins were discovered deep in Nevada's Comstock Lode, new techniques of timbering, drainage, and air circulation were devised to support shafts and tunnels blasted and bored at unprecedented depths. The mining frontier became the great laboratory of the world's mining industry.

These technological changes were part of another development in which the frontier played a crucial part - the rise of American industry. Some of the most romanticized frontier figures were essential actors in the the nation's industrialization. By the end of the Civil War mechanized meatpacking plants had appeared in the Midwest. They were prepared to satisfy a growing demand in the swelling cities, but local supplies of cattle were limited. In south Texas, on the other hand, were huge herds of rangy "longhorn" cattle. The cattle drives from Texas to railroad towns in Kansas and Nebraska, first tried in 1867, were a cheap and efficient means of linking resources and demand in the rise and expansion of a modern American industry. To do the vital work of moving and caring for the beef on the hoof, rancher-businessmen turned to their labor force on horseback - the cowboys. As railroads reached into Texas and as Native Americans were confined to reservations, the industry spread into west Texas and northward throughout much of the Great Plains.

Mining was an even more obvious case of frontier industrialization. The fortunes in gold and silver coming out of the West (an estimated $1 billion from California and $300 million from the Comstock alone) fed essential capital to a hungry economy in this age of economic transition. The largest copper mines in the world - in Butte, Mont., and Bisbee, Ariz. - provided a steady supply of a metal essential to the machinery of thousands of new factories. Workers now were wage laborers in a highly industrialized - and very dangerous - workplace. A Nevada silver mine or a gold mine in the Black Hills was essentially a modern underground factory.

Western frontier industry was financed in part by an explosive growth in corporations, another critically important national trend of the day. Mines from California to Colorado, Idaho to Arizona, were financed through corporations selling stock to wealthy and middle-class investors throughout the nation and across the Atlantic. A few western financiers grew fabulously wealthy through this corporate growth. Many of the most famous western ranches also were corporate enterprises. Wyoming's largest, the Swan Land and Cattle Company, was controlled by Scottish investors, and the largest ranch in American history, the XIT Ranch in the Texas Panhandle, was controlled by Chicago real estate investors using profits made from rebuilding after that city's great fire of 1871.

So the frontier can be seen as the cutting edge of revolutionary changes - technological and economic - moving outward from Europe and the eastern United States. It drew new regions into a global market. It carried into those regions products of industry and drew away from them resources needed in faraway factories and cities. In this sense, the frontier was a vital process in the creation of a modern world order.

Many benefits came from this process, especially as measured in material terms. The productive output of frontier regions increased. The foodstuffs of the Great Plains, the sheep and cattle of the Southwest, and the lumber of the great forests of the Pacific Northwest helped feed, clothe, and house millions. Those on the frontier had access to some of the fruits of outside industry and technology, from factory-made clothing to new medicines. Those behind the frontier's expansion hailed it as a creative force of human progress.