Not verified yet but allegedly this 15 lb. largemouth was caught in Massachusetts recently.
Yes it's far north for a bass that size but it's not unprecedented as the state record is 15 lbs. 8 oz.
Why so big so far north? Probably herring that make runs into freshwater ponds. Also the state heavily stocks waters in the state with trout.
I'm a former resident of the bay state. It's a small state but has 5000 lakes and reservoirs.
Not uncommon to have a town have it's own reservoir.