A more fundamental problem with the economic case for taxpayer-financed stadiums is the assumption that spending associated with a ballfield will be new spending, as opposed to spending shifted from other parts of the city or the metropolitan area. If people who used to go to nightclubs in D.C. start going to baseball games instead, for example, the city's economy won't be any stronger as a result.

 "Most studies find that new sports stadiums do not increase employment or incomes," 80 economists said in a recent letter to Williams and the D.C. Council. "The reason appears to be that sports stadiums do not increase overall entertainment spending but merely shift it from other entertainment venues." They said "a vast body of economic research" indicates a new D.C. stadium "will not generate notable economic or fiscal benefits for the city."

 In fact, as economists Dennis Coates and Brad R. Humphreys note in a recent Cato Institute paper, there's evidence that sports stadiums can hurt local economies. Looking at the economic performance of 37 cities between 1969 and 1996, they found "the presence of pro sports teams had a statistically significant negative impact on the level of real per capita income."

 The lack of empirical support for Williams' vision of a baseball-induced economic renaissance helps explain why he argues that, because the city plans to tax large businesses, "our residents will not be asked to pay one dime of tax dollars toward this ballpark." But as Coates and Humphreys note, "this tax increase will touch D.C. residents in some way," whether "in the form of lower wages for workers, lower asset values for corporate owners, or higher prices for consumers."

 For someone who does not hesitate to trumpet every stadium benefit, no matter how uncertain, Williams is curiously shortsighted when it comes to the project's costs.