The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System[1] in the United States; French: chaînes côtières du Pacifique; Spanish: cadena costera del Pacífico)[2] are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico.

That definition excludes the Sierra Nevada and Cascade Ranges, the Mojave (High), and Sonoran (Low) Deserts,[4] i.e. the Pacific Border province.

From the vicinity of San Francisco Bay north, it is common in winter for cool unstable air masses from the Gulf of Alaska to make landfall in one of the Coast Ranges, resulting in heavy precipitation, both as rain and snow, especially on their western slopes.

The same Winter weather occurs with less frequency and precipitation in Southern California, with the mountains' western faces and peaks causing an eastward rainshadow that produces the arid desert regions.

The breakup of Pangea 200 million years ago began the westward movement of the North American plate, creating an active margin on the western continent.

[6] Other Mesozoic terranes that accreted onto the continent include the Klamath Mountains, the Sierra Nevada, and the Guerrero super-terrane of western Mexico.

[8] As extension in the Basin and Range Province slowed by a change in North American Plate movement circa 7 to 8 Million years ago, rifting began on the Gulf of California.

However, both are considered part of the Pacific Coast Ranges due to their proximity and similar economic and social impact on surrounding communities.