Exploring the Rocky Mountain states of COLORADO, WYOMING, MONTANA and IDAHO could literally take forever. Stretching over one thousand miles from the virgin forests on the Canadian border to the desert of New Mexico, America's rugged spine encompasses an astonishing array of landscapes - geyser basins, lava flows, arid valleys and huge sand dunes - each in its own way as dramatic as the magnificent white-topped peaks. The geological grandeur is enhanced by wildlife such as bison, bear, moose and elk, and the conspicuous legacy of the miners, cowboys, outlaws and Native Americans who fought over the area's rich resources during the nineteenth century.

Apart from the Ancestral Puebloan cliff-dwellers, who lived in southern Colorado until around 1300 AD, most Native Americans in this region were nomadic hunters. They inhabited the western extremities of the Great Plains, the richest buffalo-grazing land in the continent. Spaniards, groping through Colorado in the sixteenth century in search of gold, were the first whites to venture into the Rockies. But only after the territory was sold to the US in 1803 as part of the Louisiana Purchase was it thoroughly charted, starting with the Lewis and Clark expedition that traversed Montana and Idaho in 1805. As a result of the team's reports of abundant game, the fabled " mountainmen " had soon trapped the beavers here to the point of virtual extinction. They left as soon as the pelt boom was over, however, and permanent white settlement did not begin until gold was discovered near Denver in 1858. Within a decade, speculators were plundering every accessible gorge and creek in the four states in the search for valuable ores. The construction of transcontinental rail lines and the establishment of vast cattle ranches to feed the mining camps led to the slaughter of millions of buffalo, and conflict with the Native Americans became inevitable. The Sioux and Cheyenne , led by brilliant strategists like Sitting Bull and Crazy Horse, inflicted decisive victories over the US Army, most notably at Little Bighorn - " Custer's Last Stand ." However, a massive military operation had cleared the region of all warring tribes by the late 1870s.

Most of those who came after the Native Americans saw the Rockies strictly in terms of profit: they took what they wanted and left. Small communities in this isolated terrain remain exclusively dedicated to coal, oil or some other single commodity, and all too often the uncertain tightrope walk between boom and bust is evident in their run-down facades.

Each of the four states has its own distinct character. Colorado , with fifty peaks over 14,000ft, is the most mountainous and populated, as well as the economic leader of the region. Friendly, sophisticated Denver is the only major metropolis in the Rockies. It's also the most visited, in part because it's that much more accessible, but tourist numbers remain low enough not to detract from its role as a summer paradise for cyclists and whitewater enthusiasts, and as home to the best ski resorts in the country. Less touched by the tourist circus is vast, brawny Montana , where the "Big Sky" looks down on a glorious verdant manuscript scribbled over with gushing streams, lakes and tiny communities.

Away from gurgling, spitting Yellowstone , adjacent Grand Teton park and the nearby Bighorn Mountains , vast stretches of scrubland fill Wyoming , the country's least populous state. Rugged, remote and desolate Idaho holds some of the Rocky Mountains' last unexplored wildernesses, most notably the mighty Sawtooth range.

You can expect temperatures in the high sixties all the way up to a hundred degrees Fahrenheit, between early June and early September, depending on whether you are in the high desert of Wyoming, the plains of Idaho, or the mountains of Colorado. In the mountains, you should be prepared for wild variations - and, of course, the higher you go the colder it gets. The altitude is high enough to warrant a period of acclimatization, while the intensity of the sun at these elevations can be uncomfortably fierce. Spring (the "mud season"), when the snow melts, is the least attractive time to visit the Rockies, and while the delicate golds of quaking aspen trees light up the mountainsides in early fall, by October things are generally a bit cold for enjoyable hiking or sports. Most ski runs are open by late November and operate well into March - or even June, depending on snow conditions. The coldest month is January, when temperatures below 0°F are common.

Attempting to rush around every national park and major town is a sure way to miss out on one of the Rockies' real delights - coaxing a car along the tight switchback roads that wind up and over precipitous mountain passes. At some point it's worth forsaking motorized transportation, though, to see at least some of the area by bike ; the Rockies contain some of the most challenging and rewarding cycling terrain on the continent. And of course, you cannot count yourself a visitor to the area without embarking on a hike or two.

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