State line is pretty much at a small bridge over a stream about 4 miles up (assuming you started from Rt 20). So seems like you were well up into MA.
Maybe it was further south than you were thinking because you went into Southwick?
Didn't look at the track until just now... yes, well into Mass, almost up to Westfield. And your southerly sojourn took you right behind my parents house and down to the nursery where I started off my career some 40+ years ago.