Could someone help me identify this insect?
Looks like a Bibio, sometimes referred to as "March flies" and one species in particular known as "St Mark's Fly". Yours seems unlikely to be that one because it is found in England and it seems like nowhere else.

Most likely I think yours is a Bibio vestitus from the picture below (unfortunately I wasn't able to find multiple sources corroborating this, though, so take it with some caution), and although I had trouble finding definitive distribution data, it looks like the one in your picture has the copper-colored legs, and in addition the first image below claims to be from Massachusetts. There are many many species of Bibio though so I can't be certain of species.



Bibio vestitus
Reference