The case for including agglomeration benefits within transport appraisal rests on an assumed causality between access to economic mass and productivity. Such causality is difficult to establish empirically because estimates may be subject to sources of bias from endogeneity and confounding. They...

It is difficult to separate the individual effects of the recession and the 9/11 attack. Within this severe constraint, the national economic impact of 9/11 appears to have been both modest and short-lived. This is supported by the sharper decline in industrial production in 2001 than in 2002....