Answer: It's very hard to say exactly what the problem is. White pines tend to be relatively trouble-free. The two major pests are a weevil and a disease called white pine blister rust. White pine weevils usually girdle the leader (top branch), causing it to wither and bend over. Rust diseases cause lesions on the bark.
White pines are not tolerant of certain environmental conditions, and this could be an important factor. The trees don't do well on roadsides, because they suffer severe damage from salt spray and from pollutants. If the damage on the trees affect only the side facing the road, this is probably the problem.
Before you can take any preventative measures, you'll need to identify the problem. I hope this helps!
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