What Are The 4 Major Mountain Ranges In The United States Of America?

Well, I don't have any data to back up my answer, but the only four mountain ranges I can think of are.....
 
1) Rockies
2) Appalachian
3) Sierra Nevada
4) Blue Ridge

Appalachian mountains

Following are  major mountain ranges in USA

1. Alaska range
2. Brooks range
3. Coast range
4. Black hills