The abandonment games were interesting. I have heard more than one claim that a fire in a tunnel or bridge of unknown origin seemed to conveniently happen that enables a railroad to mothball if not abandon a line.
Unlike most other modes of transportation, railroads have to pay property taxes so unused or underutilized tracks retain both a financial and legal liability.
I now consider most shortlines and branchlines as an endangered species due to the evolution of railroading. I worked for a shortline that basically was an operator for some Soo Line branches, and Soo was a good partner that competed for traffic. In addition they didn't care if we did multiple origin unit trains (splitting cars between two or three elevators) as long as we delivered them to the interchange as a single unit. Even this line has had a traffic change as the local co-op elevator at the end of the line sold out to a larger company that trucks to BNSF served elevators. Another shortline in Minnesota was former BN lines and they did not allow us to do multiple origin or co-load unit trains. We also couldn't interchange with Soo Line except for a few limited cases. The STB finally put an end to paper barriers for new traffic, but many still remain.
I have found that the last known mixed train on the SP (Pacific Lines) was between Clifton and Lordsburg, Arizona and lasted until at least 1963. I'm not sure when SP ended the service, but again I think it was just easier for SP to haul a combine instead of a caboose since they were running the train anyway. This indicated they were making an effort to provide the service, and when the time came to abandon it any complaints could be easily deflected if few if any passengers used the service.
Regarding branchlines that might generate a few thousand carloads per year that were abandoned - the current railroad business model is that a shortline must generate 100 carloads per mile annually to be profitable. This is a figure being promoted by investors, but in reality I have worked on many that did far fewer cars, you have to consider the actual operating costs. The unit train concept has really changed railroading. Most railroads don't want to handle single carloads, and do not competitively price it. A first, railroads began giving a discount if you would ship at least 5 cars from a single origin to the same destination which cut down on switching. Many customer could take advantage of this. Then it was raised to 25-27 cars and the customers could only get this rate if they added enough track to load this many cars. Then a better rate was offered for 50-54 car units. Now the railroads give the best rates for shuttle trains of 100-110 cars. So many of the smaller shippers (primarily grain elevators) that could take advantage of the 5 car rate, or invested to increase their track capacity to handle 25+ units, are now at a disadvantage due to the shuttle trains. Typically a new shuttle house with a circle track is built which gets a low enough rate from the railroads that they can pay farmers a premium so all those trucks drive past their local shortline served elevator to the regional shuttle house.
Big railroads have become extremely bad at switching or doing anything out of the ordinary. It just took over two months for someone to move an engine between central Washington and Portland, after BNSF had to replace a combo because they slid the wheels flat after not releasing the handbrake.
Over half of the current railcar fleet is now owned by private owners, not railroads. Railroads gave incentive rates for shippers supplying their own cars and paid them a mileage fee as a kickback. Once the recent depression/recession hit, the railroads quit paying anything for customer supplied cars and when railroad owned cars were sitting due to a lack of business began penalizing customers using their own cars.
Back to the narrow gauge - assuming all the narrow gauges still left in the 1960s had modernized with diesels and steel cars, or perhaps standard gauged - how many would be left today as freight common carriers?
DRGW - The Monarch branch failed because it was a single commodity. Is there any potential traffic in modern times that would support Santa Fe - Antonito - Durango/Farmington?
White Pass - Major shipper zinc mine closed and a parallel highway was opened. Several proposals have been studied to reactivate line and extend it to new mining region, but so far no one is willing to make the investment required for either standard or narrow gauge and moster trucks continue to run on government maintained highways.
SP - There isn't even a standard gauge connection to the Owens Valley now. Even the line to Mina is gone. There just is not enough mineral traffic to be competitive with trucks.
US Potash (New Mexico) - Did this close due to an exhausted supply or was it replaced by a different transportation mode?
US Gypsum - Plaster City still in business. Cost studies have been done to replace the narrow gauge but so far its continued operation is the most economic option.
Westside Lumber - Trucks a better option for what little timber was left or allowed to cut.
Sumpter Valley - Even if trucks hadn't replaced the main in 1947, this region only has operating mills left at John Day (which just dropped its night shift because it can't get enough log sales) and Boise mills at La Grande, Island City and Elgin. This region just doesn't have any government timber sales left due to environmental concerns.
Of the N-C-O (assuming it had survived), the former WP Reno branch is closed as a through route and traffic to Stead is now handled out of Reno by UP. Almost all the rest of the former SP Modoc main that was NCO is gone (no local traffic, Oregon lumber traffic dried up and what is left is rerouted). Alturas-Lakeview is owned by Lake County, OR and operated by private carrier. Has been on life support for years but is actually doing fairly well now due to one remaining lumber mill being a steady shipper, an increase in perlite traffic (which actually is trucked from many miles north of Lakeview) and a lumber mill has reappeared in Alturas. Biggest problem is the 75# rail that SP standard gauged the line with 85+ years ago.
Feel free to add to the list ....
