Why did commuter trains survive so long?

[ExCon90]

I think a certain critical mass of population was necessary for rail commuter service to exist in the first place. By the end of the war, even Cleveland, New Orleans, and St. Louis only had one train a day (Erie to Youngstown, L&N to Ocean Springs, and MP to Pacific). Of the cities mentioned, only Detroit and Pittsburgh had what could be considered a decent commuter service to lose, and that was predominantly weekday rush hours only. I would say that only Boston, New York, Philadelphia, and Chicago were big enough to rate a 7-day, all-day commuter service constituting a meaningful element of travel within their metropolitan areas.

[amtrakowitz]

Not if you judge by size of urban areas. Detroit ranks 11 (just behind Boston) and SEMTA's single-line commuter rail service ended in 1983. San Francisco/Oakland ranks 13, and the extent of its rail systems is more than merely notable. Lots of cities of high population without commuter rail on that list.

[GWoodle]

[You sure that commuter rail service is so universal? Many cities that used to have commuter rail no longer have it; most prominent are Detroit, Cincinnati and Pittsburgh. Some cities have brought back commuter rail, but only on a limited scale (e.g. Dallas, Minneapolis, Nashville).[/quote]

Don't put Nashville in the list of cities that lost commuter service. The Tennessee Central was a poor line that should never have been built. It only exists in the Music City Star as a "cheap" way to rebuild a railroad from the ballast up. The L&N was never a large commuter carrier. The L&N was a decent LD carrier from the North to the South. One route connected Chicago & St Louis with Atlanta & Florida. The other route linked Cincinnatti with Mobile & New Orleans.