Implicit in many discussions of labour market policy is the assumption that, in the absence of interventions, the operation of the labour market is well-approximated by the perfectly competitive model. The merits or demerits of particular policies is then seen as a trade-off between efficiency...

This paper shows, using data from both the US and the UK, that average plant size is larger in denser markets. However, many popular theories of agglomeration – spillovers, cost advantages and improved match quality – predict that establishments should be smaller in cities. The paper...