Which land form is not found in the western united states

Coastal Plains  is not found in the western United States

Explanation:

A landscape is part of the ground on the surface of the Earth. The four main types of vegetation are mountains, valleys, plateaux and plains. Small landforms are buttes, canyons, lakes, and dams. The motion of the tectonic plates beneath the earth will produce shapes by moving valleys and mountains.

In western United States, Coastal Plains are not found.  

A close to zero-lying coastal plain located close the seashore sea. Throughout Alaska and the south-east of America are among the highest coastal plains. North America's Gulf Coastal Plain expands north of the Lower Mississippi Gulf to the Ohio River, approximately 980 miles away.