Check out this graph from the Institute of Policy Studies (original PDF here).
If you look at the left column, government spending on mass transit creates the most jobs on a number basis, and the second highest number of jobs on a total wages basis. Giving people money for personal consumption, as Congress and the President have just done, is basically the worst way.
The thing that they authors didn’t take into account was long-term benefits of the investments, which make domestic consumption and health care look better than they actually ought to. For example, defense spending created the Internet, which has created entire economic sectors, and education spending creates a better educated work force which has downtstream effects on the future generation’s earning prospects. Similarly, what has been the total return-on-investment for New York City’s 100-year-old subways?
Obviously, the other Washington is trying to give a short term “shot-in-the-arm” to economy, so the long term effect wasn’t as important to their decision. However, this does give credence to the idea that, in the long run, mass transit can provide significant economic stimulation. I think it’s worth noting that spending $152 billion for 300 million people averages a little more than $500 per person. Extrapolating that to the nearly two million folks in King County you’d get almost one billion in federal money right there, or $1.8 billion over the entire Sound Transit district.