The physical geography of North America is dominated by an immense belt of mountains and related landforms stretching along the continent’s western margin. This vast, complex zone is not composed of a single, continuous chain but is instead a collection of many distinct mountain ranges, basins, and plateaus. Determining the single largest mountain feature requires identifying the comprehensive system that encompasses them all. This massive western belt represents the largest mountain system by both overall extent and total volume of uplifted crust on the continent.
Identifying the North American Cordillera
The largest mountain system in North America is the North American Cordillera. This term describes the entire wide expanse of mountain ranges and associated features that form the continent’s western “backbone.” The system covers approximately 4,000 miles (6,400 kilometers) from north to south.
It begins with the Brooks Range in Alaska, extends through the Yukon Territory and British Columbia, and continues southward through the Western United States. It finally terminates in the Sierra Madre Occidental and Oriental ranges of Mexico. The Cordillera is an interconnected, parallel sequence of mountain chains. This colossal system is a segment of the larger American Cordillera, which runs continuously from Alaska down to the Andes Mountains in South America. The North American portion is therefore a geological super-province defined by its contiguous footprint and its shared history of tectonic activity. Within the United States, this system covers nearly the entire area west of the Great Plains.
The Major Component Ranges
The Cordillera’s width and scale are generated by its three primary parallel belts, each with a distinct character.
The Eastern System
The Eastern System, also known as the Laramide Belt, is situated furthest inland and includes the Rocky Mountains. This range stretches over 3,000 miles (4,800 kilometers) from northern British Columbia down to New Mexico, forming the system’s eastern boundary.
The Interior System
The Interior System occupies the middle portion of the Cordillera. It is characterized by significant mountain blocks separated by intermontane plateaus and basins. This belt includes the Sierra Nevada, the Cascade Range, the extensive Basin and Range Province, and the Columbia Mountains in Canada.
The Western System
The Western System, or Pacific Coast Belt, runs parallel to the Pacific Ocean shoreline. This grouping includes the rugged Coast Ranges of California, Oregon, and Washington, the Alaska Range, and the Coast Mountains of Canada. These coastal ranges represent the most recently formed components of the system.
Geological Formation and Growth
The formation of the North American Cordillera resulted from prolonged and intense tectonic activity along the continent’s western edge. For hundreds of millions of years, oceanic plates, such as the Farallon Plate, were subducting beneath the North American Plate. This process created immense compressional forces that buckled and thickened the continental crust.
A significant part of the system’s growth came from terrane accretion, where fragments of island arcs and pieces of oceanic crust were scraped off the subducting plate and welded onto the continent’s edge. The coastal ranges are largely composed of these accreted terranes.
The Rocky Mountains, forming the easternmost part of the system, were primarily uplifted during the Laramide Orogeny (80 to 55 million years ago). This event is notable because the deformation occurred far inland, which geologists attribute to a shallow angle of subduction by the Farallon Plate. This “flat-slab” subduction transmitted compressional stress far beneath the continent, raising the interior mountains.
In contrast, the Cascade Range is a modern volcanic arc, defined by active stratovolcanoes like Mount Rainier and Mount Hood. These mountains are a direct result of ongoing subduction, where the oceanic plate descends deeper, melts, and the resulting magma rises to the surface.
Defining the Highest and Lowest Points
The North American Cordillera contains the highest point on the entire continent: Denali. Located in the Alaska Range, this summit rises to an elevation of 20,310 feet (6,190 meters) above sea level. Denali’s height is a product of the ongoing collision and convergence of tectonic plates in the far north.
The lowest point in North America is also found within the Cordillera system. This is the Badwater Basin in Death Valley, California, which sits 282 feet (86 meters) below sea level. Death Valley is part of the Basin and Range Province, an area that has undergone extensive crustal extension and block faulting, creating deep structural depressions alongside uplifted mountain ranges.