A group called Smart Growth America has a new report out showing that when it comes to job creation, it's better to spend stimulus funds on public transportation projects as opposed to building roads and highways. Public transportation projects create nearly twice as many jobs per dollar spent, in fact.Here's the chart:Why is this the case? Smart Growth America says it's because public transportation projects end up spending less money on land acquisition, and require more buying and maintenance of vehicles (which require man-hours to make and repair).The one slightly fishy thing about this chart is that the jobs are measured in "job-months." It's possible that this conceals an important difference in terms of which kinds of projects yield stable, long-term employment as opposed to, say, a month long contract gig.But assuming that's not the case, this is convenient news. After all, it's the public transportation, and not the car infrastructure, that we really need in the long term. Maybe we should throw a bit more money that way.