That's a very vague question? Define important?
I would say the White Mountains (Washington/Jefferson),
for their scientific value (weather)
Appalachian
Appalachian
The Appalachian Mountains is the largest mountain range in the eastern part of the US, stretching from Alabama to Canada.
The Appalachian mountain range
The Appalachians is a mountain range that runs through the eastern U.S.
The Appalachian Mountain Range is in the eastern US.
The Appalachian Mountain Range is in the eastern US.
The Appalachian Mountain Range is in the eastern US.
The Appalachian Mountain Range is in the eastern US.
Appalachans
Appalachian..
Applachin mountains