I can say from family history, my grandparents, both sides moved to Lawrence, MA during the deparession. and my parents were raised there in the 30's and 40's. Many family members worked at the mills at times.
The wool mills suffered when clothing went to polyesters, etc. With that came the closing of the mills and the death of the city began.
My family visited my grandparents in the 70's and the decline was evident. Low rents, declining neighborhoods, gave landlords motivation to arson there own properties.
I know from a cousin, firefighter who is retired now that they had a high incidence, above average, of suspicious fires. We're talking about tenament housing here. Not the best residents. Drugs, crime…
I would suspect alot of these cases are arson. It has just reached a tipping point.
Btw my family moved out of Lawrence.
Think of it as a smaller version of Chicago.
And, on a grander scale, what if developers had their eyes on that area? It's about 15 or so miles from Boston…