Virginia’s new rail system-another line, from Washington 33 miles west to Manassas, opened in late June-is the latest sign of America’s new love affair with an old form of transportation: commuter trains. Commuter-rail ridership has risen 25 percent in the past decade, to 325 million passengers a year. New lines are sprouting as states struggle to meet tighter federal clean-air standards, and seats and parking places are in short supply. Enthusiasm is so high that transit agencies in Massachusetts and Maryland have laid on new trains just to get baseball fans to the ballpark.

Even carbound Los Angeles is getting into trains, big time: three routes set to open in October will spare commuters two hour drives to downtown. San Diego will start a 42-mile diesel run from Oceanside to downtown in 1994. Older systems are expanding, too. The terminus of San Francisco’s sole commuter train is being extended south from San Jose to Gilroy. New Jersey Transit, which now runs 11 rail lines, hopes to reopen a long-closed route to the northwestern part of the state in 1997. Massachusetts has a $480 million project underway to restore two lines south of Boston that last saw commuter trains in 1959.

The rediscovery of trains is due largely to the relentless sprawl of development. Commutes are longer than ever, and the political and environmental obstacles to widening roads in urban areas are steep. When Maryland opened rail service last year on a 40-mile line from Perryville to Baltimore, officials discovered that most of their 600 daily riders head not to Baltimore but to Washington, D.C., 40 miles beyond. Says state transit chief Ronald Hartman, “The day of the long-distance commute is here.”

Commuter trains come cheap, since the tracks are already in place. The entire Virginia Railway Express project cost $131 million, about the same as a mile of subway line. The major expenditures are for passenger cars and parking lots. Money is available thanks to a 1991 law allowing states to spend part of their federal transportation grants on railroads rather than highways. Of course, no commuter run pays its way: only a subsidy can keep tickets competitive with free roads and employer-supported parking. But some lines are trying hard to hold the lid on operating costs. By dispensing with manned ticket offices and selling tickets from machines and convenience stores instead, the Virginia trains are projected to cover 70 percent of their expenses.

The freight railroads, which once regarded commuter trains as a nuisance, have changed their tune. Freight trains run on tighter timetables than they used to, so the railroads can collect government subsidies for running passenger lines without disturbing their other business. “Operating a railroad train is operating a railroad train,” says D J Mitchell of Burlington Northern Railroad. The freights are even competing to run proposed commuter lines in Houston, Seattle and other cities. Enjoy the ride-and good luck finding a parking spot at the station.