Rocky Mountain Trench in the context of Kootenay National Park

The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch 3,000 mi (4,800 km) in a straight-line distance from the northernmost part of Western Canada, to New Mexico in the Southwestern United States. Depending on differing definitions between Canada and the U.S., its northern terminus is located either in northern British Columbia's Terminal Range south of the Liard River and east of the Trench, or in the northeastern foothills of the Brooks Range/British Mountains that face the Beaufort Sea coasts between the Canning River and the Firth River across the Alaska–Yukon border. Its southernmost point is near the Albuquerque metropolitan area, adjacent to the Rio Grande rift, and north of the Sandia–Manzano Mountain Range, also near Santa Fe, New Mexico. Being the easternmost portion of the North American Cordillera, the Rockies are distinct from the tectonically younger Cascade Range and Sierra Nevada, which both lie farther to its west.

The Rockies formed 55 million to 80 million years ago during the Laramide orogeny, in which a number of plates began sliding underneath the North American plate. The angle of subduction was shallow, resulting in a broad belt of mountains running down western North America. Since then, further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks and valleys. At the end of the last ice age, humans began inhabiting the mountain range. After explorations of the range by Europeans, such as Sir Alexander Mackenzie, and Anglo-Americans, such as the Lewis and Clark Expedition, natural resources such as minerals and fur drove the initial economic exploitation of the mountains, although the range itself has never experienced a dense population.

The Canadian Rockies (French: Rocheuses canadiennes) or Canadian Rocky Mountains, comprising both the Alberta Rockies and the British Columbian Rockies, is the Canadian segment of the North American Rocky Mountains. It is the easternmost part of the Canadian Cordillera, which is the northern segment of the North American Cordillera, the expansive system of interconnected mountain ranges between the Interior Plains and the Pacific Coast, that runs northwest–southeast from central Alaska to the Isthmus of Tehuantepec in Mexico.

Canada officially defines the Rocky Mountains system as the mountain chains east of the Rocky Mountain Trench extending from the Liard River valley in northern British Columbia to the Albuquerque Basin in New Mexico, not including the Mackenzie, Richardson and British Mountains/Brooks Range in Yukon and Alaska (which are all included as the "Arctic Rockies" in the United States' definition of the Rocky Mountains system). The Canadian Rockies, being the northern segment of this chain, is thus defined as comprising the central-eastern section of the North American Cordillera, between the Prairies of Alberta and the Liard Plain of northeastern British Columbia to the east and the Interior Mountains/Plateau and Columbia Mountains to the west. It is divided into the Northern Rockies (which is further subdivided into the Muskwa and Hart Ranges) and Continental Ranges, separated by the McGregor River valley, the McGregor Pass and the Kakwa River valley.

The Columbia Mountains are a group of mountain ranges along the Upper Columbia River in British Columbia, Montana, Idaho and Washington. The mountain range covers 135,952 km² (52,491 sq mi). The range is bounded by the Rocky Mountain Trench on the east, and the Kootenai River on the south; their western boundary is the edge of the Interior Plateau. Seventy-five percent of the range is located in Canada and the remaining twenty-five percent in the United States; American geographic classifications place the Columbia Mountains as part of the Rocky Mountains complex, but this designation does not apply in Canada (despite a British Columbia government tourism campaign to rebrand their southern portion as the "Kootenay Rockies"). Mount Sir Sandford is the highest mountain in the range, reaching 3,519 metres (11,545 ft).

The Muskwa Ranges are a group of mountain ranges in northern British Columbia, Canada. They are part of the Northern Rockies section of the Rocky Mountains and are bounded on their west by the Rocky Mountain Trench and on their east by the Rocky Mountain Foothills. They are delimited on the north by the Liard River and on the south by the Peace Reach of the Lake Williston reservoir (formerly the Peace River), south of which the next major grouping of the Rockies is the Hart Ranges.

The Muskwa Ranges cover a surface of 97,388 square kilometres (37,602 mi) and stretch for 424 kilometres (263 mi) from north to south.