Wikipedia's page on the Newburyport RR is pretty good: http://en.wikipedia.org/wiki/Newburyport_Railroad" onclick="window.open(this.href);return false; The 1941 date for abandonment between Topsfield and Newburyport (current depot location) is accurate. The original passenger station on Pond St. survived as Newburyport's freight station until about 1952. This was replaced by a First National, now a CVS. The City RR branch to the waterfront was active till about 1967. But I'm pretty sure the Danvers - Topsfield segment was abandoned about 1972 due to traffic to the feed mill & team track not justifying required maintenance. This was not long after I rode it on an RRE trip.
Actually several years after that, jb. Boxford resident here who spent late 1972-76 in the Air Force and enjoyed "hunting" the Essex County locals when I was home on leave. I worked up the courage to climb the steps to Salem Twr several times and built a rapport with friendly crew there who would give a head's-up when something would head up to Danvers and (far more rarely) to Topsfield. It was certainly a different world then!
The Essex County Coop would generally get two boxcars weekly at the Topsfield Freight House during my high school years at Masconomet Regional. Motive power at that time, '68-'72, was generally a GP7, more rarely a GP9 or SW8.
My last photograph, nearly worthless as a faded Instamatic shot in the dark, is an SW9 and single boxcar crossing Route 97 just below the fairgrounds headed back toward Danvers and then Salem, dated October, 1977.
I have the recollection of my mom, who worked at a dentist office in Danvers, telling me of one more train on the branch from Topsfield some short time later, which would be the last time I was aware of service above Danvers. I can't offer an exact timeframe for that other than some time within reasonable proximity to late 1977.
As a one-time local with a strong interest, it has always surprised me that we can't identify a truly definitive date for last service to Topsfield.
Bob