How are the Alaskan mountains connected to the Rocky Mountains and the Pacific mountain system?

Structurally, the mountain ranges of Alaska are considered northwestward continuations of the Rocky Mountains and the Pacific mountain system of North America.1

The connection is organized as follows:

• Rocky Mountains: The Brooks Range in northern Alaska serves as an extension of the Rocky Mountains, stretching in an east-west arc from the Canadian border across the state.1
• Pacific Mountain System: The southern coastal mountains of Alaska are part of the Pacific mountain province. The St. Elias Mountains at the Canadian border merge to the southeast into the Boundary Ranges, which form the Alaskan panhandle. This system is characterized by ongoing tectonic activity, including the rapid underthrusting of the Pacific Plate beneath the southern Alaskan coast, which continues to shape the region's high, rugged topography.12