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