Question

What mountain range runs north and south in the United States, starting in Idaho and ending in New Mexico?

Answer 1

The Rocky Mountains are the most extensive mountain range in the western United States.

Explanation:

The Rockies, as they are called for short, also extend further north across the border into Canada. The entire Rocky Mountain range overlaps six western states and two Canadian provinces. See https://en.wikipedia.org/wiki/Rocky_Mountains.

As advertisers sometimes say, "But wait, there's more." Mountain ranges around the world are organized into larger groupings, and that includes the Rockies. The North American Cordillera (https://en.wikipedia.org/wiki/North_American_Cordillera) includes not only the Rockies but essentially all the mountains in weatern North America, from Alaska into Mexico.