Business support policies designed to raise productivity and employment are commonworldwide, but rigorous micro-econometric evaluation of their causal effects is rare. Weexploit multiple changes in the area-specific eligibility criteria for a major program to supportmanufacturing jobs...

In this paper we show that the recent model by Duranton (AER, 2007) performs remarkablywell in replicating the city size distribution of West Germany, much better than the simplerank-size rule known as Zipf´s law. The main mechanism of this theoretical framework is thechurning of industries...