The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. The Rocky Mountains stretch more than 3000 miles from British Columbia to New Mexico, extending through Canada and much of the breadth of the contiguous United States. The highest peak is Mount Elbert, in Colorado, which is 14,440 feet above sea level. Mount Robson is the highest peak in the Canadian Rockies. The Rocky Mountain System is a United States physiographic region.
The Rocky Mountains are commonly defined to stretch from the Liard River in British Columbia, down to the Rio Grande in New Mexico. The mountains can also be considered to run to Alaska or Mexico, but usually those mountains are considered to be part of the entire American cordillera, rather than part of the Rockies.
The Rocky Mountains were created during what geologists call the Laramide orogeny during a period that started 70 million years ago and ended 30 million years ago. After the mountains were raised to nearly the height of the Himalaya today, part of western North America started to stretch, breaking up much of the south western part of the mountain plateau into horsts (ranges) and grabens (basins). This area is now called the Basin and Range Province.
On July 24, 1832, Benjamin Bonneville led the first wagon train across the Rocky Mountains by using Wyoming's South Pass.
Human population is not very dense in the Rocky Mountains, with an average of four people per square kilometer (2.5 per square mile) few cities with over 50,000 people. However, the region is an extremely popular tourist destination. People from all over the world visit the beautiful sites to hike, camp or engage in mountain sports.
The Rocky Mountains have a highland climate. The average temperature in the Rockies per year is 43 °F (6 °C). July is the hottest month with an average temperature of 82 °F (28 °C). In January, the average monthly temperature is 7 °F (−14 °C), making it the coldest month in the Rockies. The average precipitation per year is approximately 14 inches (360 mm).
The summers in the Rockies are warm and dry. The average temperature in summer is 59 °F (15 °C) and the average precipitation is 5.9 inches (150 mm). Winter is usually wet and very cold, with an average temperature of 28 °F (−2 °C) and average snowfall of 11.4 inches (29.0 cm). In spring, the average temperature is 40 °F (4 °C) and the average precipitation is 4.2 inches (107 mm). And in the fall, the average precipitation is 2.6 inches (66 mm) and the average temperature is 44 °F (7 °C).