They are also very rural.
VT is generally very rural.
However, southern NH and Southern ME are not.
75%(or more) of the NH population lives within 20 miles of the Mass border. Many NH citizens live in NH and work in Mass. Boston is only 55 miles away from Nashua. Very few people live in the northern part of the state.
Maine is similar in that most of the people live from Portland down to the NH border within 10 miles of the Atlantic Ocean. NOBODY, I mean NOBODY lives in northern Maine.
So, it is very rural in some parts and crowded in others. In that way it is similar to most other states in the union.
Rural has nothing to do with it.
The top ten states with the LOWEST population density are:
1. Alaska
2. Wyoming
3. Montana
4. North Dakota
5. South Dakota
6. New Mexico
7. Idaho
8. Nebraska
9. Nevada
10. Kansas
https://www.worldatlas.com/articles/least-densely-populated-u-s-states.html
Yet, all of these states have higher crime rates than VT,NH & ME.
How do you explain that?