The Laramide Orogeny is the major mountain-building event responsible for the formation of the Rocky Mountains.

The Laramide Orogeny was a period of mountain building that occurred in western North America from roughly 80 to 55 million years ago. This tectonic event involved the subduction of the Farallon Plate under the North American Plate, causing uplift and deformation of the Earth's crust. This process is the primary geological event responsible for creating the Rocky Mountains, shaping their current form.