THE FEDERAL government has a lot on its mind these days. A war in Afghanistan. Fiscal reform. Health care. With so many genuine issues to address, you wouldn’t have thought that Washington would also be trying to figure out a new way to get tourists from Southern California to the Las Vegas strip.

But you would be wrong. The Federal Railroad Administration is considering lending $4.9 billion to a company called Desert Xpress, for the purpose of building a high-speed rail line to Las Vegas from Victorville, Calif., some 81 miles east of downtown Los Angeles.

The brainchild of several wealthy Las Vegas casino moguls, Desert Xpress enjoys the backing of Senate Majority Leader Harry M. Reid (D-Nev.) and has already secured approvals from the Bureau of Land Management, the Army Corps of Engineers and the Fish and Wildlife Service, among other federal and state agencies. It is pursuing about $1.6 billion in private financing.

All that’s left is the Federal Railroad Administration’s okay on the loan. According to a recent Associated Press report, the $4.9 billion loan would be three times as much as all previous lending by the Railroad Rehabilitation and Improvement Financing (RRIF) program, a little-known pot of low-interest, long-term credit previously used mainly to upgrade existing lines.

The proposed line’s advertised public benefits are the same as those claimed for all high-speed rail projects: reduced carbon emissions, less air and auto traffic, and, of course, jobs, jobs, jobs. What makes this one unique is that it would be a non-stop route whose Western end, Victorville, would function as a gathering point for people from all across Southern California. They would park their cars and then board the train for Vegas. In theory, that’s no different from driving to an airport and leaving your car. And once you reached the train, it would take only 80 minutes to hit Vegas, as opposed to a minimum four-hour drive each way.

In theory. But if this train is such a good idea, business-wise, how come private banks aren’t lining up to finance it? Previous high-speed rail projects around the world have been plagued by poor ridership, requiring government subsidies to continue operation. You might save travel time by taking the train instead of a car — as long as you’re content to depend on the train’s schedule.

The train’s backers project an average round-trip L.A.-Vegas fare as low as $89 in 2017, with luxury amenities available. (We’re skeptical; the one-way Acela Express fare from Baltimore to New York, a similar distance, is more than $200.) In any case, you can already fly round-trip for as little as $109, with no drive to Victorville. A bus service called My Party Ride will take you and two dozen friends for $99 each and include burgers and drinks. The train won’t help Las Vegans visit Los Angeles, unless they want to ride to Victorville and rent a car for the rest of the trip.

As for jobs, any that the Vegas train creates will come at the expense of alternative uses of the money — upgrading the Northeast Corridor to accommodate higher-speed trains comes to mind — not to mention My Party Ride and other competing businesses, large and small. The new line might be a boon for Victorville, but the shift in traffic could hurt neighboring Barstow. If the casino moguls want a train, let them build it with their own money; taxpayers shouldn’t have to go along for the ride.