Northwestern Colorado is a region of the state of Colorado in the United States of America. It is a diverse area of both red rock mesas and snow capped mountain peaks, as well as the headwaters of the Colorado River. This Rocky Mountains region includes a majority of the state's most popular ski resorts, places like Breckenridge, Aspen and Vail. It is also home to the Western Slope's biggest city, Grand Junction.
Broadly, this region is bounded on the:
Region boundaries in Colorado tend to be somewhat controversial (even in day-to-day life in the state) and are done in an ad-hoc way here. If you're expecting to read about some destination in this article and can't find it, check in the neighboring Front Range, Southwestern Colorado, and even South Central Colorado sections to see if it's covered there.
For a quick list of all Colorado's ski resorts, take a look at Skiing in Colorado.
Normally, this section is reserved for places of scenic natural wonder, as well as geologic interest. Here are a few of the region's highlights:
This area is dominated by its geology. It is fairly evenly divided between some of the highest, snow-covered peaks in the Rockies and the beginning of the sandstone canyon and mesa country that is typical of the high-desert Colorado Plateau. The two biggest geologic features in Northwestern Colorado are the Western Slope of the Continental Divide and the mighty Colorado River, fed by the mountain snow of the Rockies and eventually carving out the Grand Canyon in Arizona.
The mountains are still growing, thrust upwards by a subducting tectonic plate that scientists hypothesize is situated at an odd angle. It explains why Northwestern Colorado is curiously free of any volcanoes similar to the Cascades in Washington and Oregon. (Although there has been volcanic activity in the past, and Northwestern Colorado is dotted with geothermal pools in places like Steamboat Springs and Glenwood Springs). Northwestern Colorado boasts Mount Elbert near Aspen. It rises 14,433 ft (4268m) above sea level and is the highest mountain in the entire Rocky Mountain range.
A geological formation characteristic of the mesa portion of the region are the Bookcliffs that are shown to good advantage around Grand Junction. A legacy of this geology is that the region is famous for its Jurassic-era fossils, found throughout the Morrison Formation. Dinosaur National Monument, along the Utah state line and extending into that state, was formed to preserve the enormous fossil beds found there, which are still yielding remarkable paleontological discoveries. Delta, just south of the region in Southwestern Colorado, as well as Grand Junction have large fossil quarries.
There is an economic divide, as well. Northwestern Colorado is a region of both small, struggling towns and high-end ski resorts (some of the richest and most expensive in the world). The ski resorts are a playground for jet-setting millionaires and billionaires, with multimillion dollar mansions and high costs of living. Outside of these pockets of excess are large rural areas, home to ranches and orchards. Northwestern Colorado is also where Colorado's Wine Country is located, the state's answer to Napa and Sonoma in California. Sizable portions of Northwestern Colorado are public lands owned by either the federal government or the state. So there are plenty of opportunities for hiking, camping, fishing, hunting, mountain biking, rafting and other forms of recreation.
Between 250 and 1300 AD, the Fremont people were the area’s first inhabitants. Their culture can still be glimpsed today in the many petroglyphs and pictographs they created on canyon walls in the mesa portion of the region. Circa 1500, the Ute nation moved into Northwestern Colorado.
With the conquest of the Aztec Empire in Central America in 1521, the Spanish formed the Viceroyalty of New Spain and claimed a large part of North America for themselves, including a nebulous region around Northwestern Colorado. The borders were not firmly fixed on a map, and the Spanish only managed to settle as far as South Central Colorado.
During the 19th century, the area was very much in dispute with a young nation, the United States. After the Louisiana Purchase of 1803, the U.S. claimed all the land south and west of the Arkansas River. Spain declared a large trade zone around its colony of Santa Fé de Nuevo Méjico, a claim the U.S. challenged. In 1806, Zebulon Pike led a U.S. Army expedition into the area, "discovering" Pike's Peak in the process, but Pike never reached as far as Northwestern Colorado. A contingent of Spanish cavalry apprehended and arrested the Pike expedition in South Central Colorado, eventually expelling them from New Spain. The U.S. relinquished its claim on the region as part of the purchase of Florida from Spain with the Adams-Onís Treaty of 1819.
In 1821, the Viceroyalty of New Spain successfully revolted, splitting with the Spanish crown. Northwestern Colorado may have become part of Alta California, a province in the new nation of Mexico.
Hoping to develop the area, Mexican officials opened the land up to mountain men, trappers and traders. Between 1821 and 1840, explorer Antoine Robidoux ventured through the region in search of beaver pelts. With this influx of adventurers and speculators came many of the men who would later lead U.S. Army expeditions and Government Surveying parties through the area: Kit Carson, "Pathfinder" John Charles Fremont and Captain John Gunnison.
In 1846, the U.S. Army invaded and defeated Mexico in the Mexican-American War. With the Treaty of Guadalupe y Hidalgo, the U.S. gained control of Northwestern Colorado, as well as California, Nevada, Utah, and portions of Arizona, New Mexico and Wyoming.
In 1849, the Mormons established the Provisional State of Deseret, which included parts of Northwestern Colorado, a claim the U.S. refused to recognize. For the next 20 years, the Mormons refused to settle east of the north-south running Green River.
While the U.S. was busy expanding its territory, the Utes were fighting a rear guard action, with intermittent settler encroachments on their lands. Friction between the Utes and whites over resources was inevitable. In 1868, the U.S. Government and the Ute Indians signed a treaty that designated Northwestern Colorado as part of the Ute reservation. But the area's rivers offered both a reliable source of water and arable land. This was compounded by the discovery of gold and silver in the San Juan Mountains to the south. There was also a missionary spirit amongst the whites, who saw it as a God-driven destiny to convert the nomadic Utes to Christianity and an agrarian way of life. These factors proved to be too great for the settlers to resist.
Determined to turn them into farmers, the head of the government's Indian Agency, Nathan Cook Meeker, approached the Utes with a mixture of arrogance and hostility. He plowed up a Ute horse-racing track to plant a field, and later engaged in a fist fight with the owner of the race track. In 1879, Meeker telegraphed for military assistance, and the Federal government responded with around 200 soldiers to police the area. The situation was handled with mutual mistrust on both sides, and several skirmishes occurred. The crisis culminated with the Utes killing several whites at the Indian Agency (including Meeker) and launching the so-called Ute War. Initially successful, the Utes were forcibly relocated to Utah, and Southwestern Colorado, near Cortez.
The Uncompahgre Reservation was opened to settlers in the fall of 1881. Settlers poured into the area. Towns like Paonia, Grand Junction, Meeker and Craig were rapidly established. For the next 80 years, farming and ranching were the staples of the region's economy. Mining towns like Aspen, Breckenridge and Leadville capitalized on the silver and gold bonanzas.
Post World War Two ushered in an area of unprecedented prosperity for Northwestern Colorado, with the founding of area's modern ski resorts. The second half of the 20th century witnessed the birth of Snowmass Village, Vail, Beaver Creek, Copper Mountain, Arapahoe Basin, Vail, and Keystone. Grand Junction grew into a regional hub to service the ski towns, as well as a boom and bust community of uranium and oil shale mining, and natural gas exploration. The population of this region continues to grow as people fall in love with its natural beauty and many recreational opportunities.
The area is largely English-speaking, with a handful of Spanish speaking communities like Minturn near Vail. There is a wide circle of Spanish speaking laborers who are the working class backbone of the mountain resorts, energy, construction and hospitality industries. At the opposite end of the spectrum are Central and South America's moneyed ruling class, who flock to Vail between Christmas and New Year's. See WikiTravel's Spanish phrasebook for more information on how to better engage both groups.
Also, within the ski towns, there are large, developed exchange programs with college-age students from Europe and South America. You will find them running the ski lifts and equipment rental shops, so hearing French, German, and Italian is not uncommon during the ski season. All, however, are required to speak English.
To visit Northwestern Colorado, travelers are going to have fly and/or drive.
Taxi service is also available at the airport.
The following companies offer shuttle/limo service from DIA, Eagle County and Aspen airports.
Amtrak  serves Grand Junction and Glenwood Springs with the California Zephyr , which runs daily between Emeryville (in the San Francisco Bay Area) and Chicago. Amtrak and AAA partner to run several Wine Trains between Denver and Grand Junction each spring. 
The major artery through the region is Interstate 70. Weather-wise, there are three distinct micro-climates along I-70 in Northwestern Colorado. Conditions are highly variable depending on both the altitude and terrain. The weather can be blizzard conditions on the Eastern Slope of the Continental Divide in South Central Colorado, cloud cover on the Western Slope, and sunny west of Glenwood Canyon near Glenwood Springs.
During the winter, heavy ice and snow are a concern on the mountain passes, which can make driving difficult and slow going. Always check the weather and road conditions  before heading out. Even on a clear winter's day, make sure your vehicle's wiper fluid reservoir is full. The Colorado Department of Transportation (CDOT)  spreads both sand and magnesium chloride on the roads, which makes for an impenetrable, gluey mess on your windshield.
In the summer months, it's not uncommon to see the shoulders of the highways littered with broken-down vehicles that could not handle the steep grades and high altitude air of the Rocky Mountains. If you are venturing from a lower altitude, make sure your car can handle mountain driving. Thinner air means you will be burning more gasoline. Also, with so many steep grades, expect to gear down to avoid unnecessary friction to your brake pads.
During peak times, I-70 can get very crowded and it is not unheard of for a trip from Eagle and Summit Counties to Denver to take 3 hours or more (Allow for 5 from Pitkin County). Peak times are weekend afternoons (2 pm- 6 pm) both in the summer and winter. Plan accordingly and either leave in the morning, or leave after 5 pm in the winter.
The majority of the ski towns offer bus service around the resorts and to the slopes. Grand Junction and Meeker have public transportation, as well.
World class dining is available in all the ski resorts. There are a variety of restaurants available in Grand Junction, as well.
There are trendy bars, brewpubs, as well as honky tonks and a handful of authentic mining-era 19th century saloons. The mountain resorts are famous for their apres-ski nightlife and clubs.