MA highways are moving 75-80mph when traffic permits, regardless of whether they have a posted 55 or 65mph speed limit. NH is only a few mph less typically.
Don't know about there, but in Oregon you just know where it's enforced. The limit here is 55 everywhere, but if you can get a clear stretch you can drive 80mph on I-5 without being stopped anywhere within Portland city limits. Once you get a little outside, the state police will stop you for going 60.
MA highways are moving 75-80mph when traffic permits, regardless of whether they have a posted 55 or 65mph speed limit. NH is only a few mph less typically.