We analyze the first data set on consistently defined functional urban areas in Europe and compare the European to the US urban system. City sizes in Europe do not follow a power law: the largest cities are "too small" to follow Zipf's law.

We discuss important features and pitfalls of panel-data event study designs. We derive the following main results: First, event study designs and distributed-lag models are numerically identical leading to the same parameter estimates after correct reparametrization. Second, binning of effect...