PhD graduates are twice as likely to be placed at a university if their PhD advisor has a co-author there. The importance of the collaboration network for placement has doubled between 1990 and 2014. Network hires are positively selected on observables, but we find no evidence for revelation of private information about graduates.

We study a reform that eased cross-border commuting from France to the high-wage Swiss labor market. Using a difference-in-difference strategy comparing French border labor markets with unaffected inland markets, we find: Wages increase among mid- and low-skill workers employed in France; employment in France does not decline overall and increases among low-skill workers; population, labor force participation and unemployment rise in France. We interpret the effects with an equilibrium search model where labor demand and supply are endogenous: The reform increased the value of local job search, drawing more workers into the labor force and lowering labor market tightness.

We establish two stylized facts: IT investment is highest in firms in large and expensive cities, and the decline in routine cognitive occupations is most prevalent in large and expensive cities. To explain these facts, we propose a model mechanism where the substitution of routine workers by IT leads to higher IT adoption in large cities due to a higher cost of living and higher wages. We estimate the spatial equilibrium model to trace out the effects of IT on the labor market between 1990 and 2015 and find that the fall in IT prices can explain a substantial share of the observed displacement and sorting patterns.

Labor market dynamism, measured by flows of workers between employers, declined substantially in the US and employment polarized into low and high-skill jobs. This paper shows the two trends are linked. I provide a framework to study employment and worker flows in presence of two-sided heterogeneity. Within an estimated version of the framework I find that routine-biased technological change accounts for about one-third of the decline in job-to-job mobility for workers without a college degree, while the remaining decline in mobility is mainly driven by a decline in the dispersion of match-specific productivity and its innovation rate.

Large cities are more productive and generate more output per person. Using data from the UK on energy demand and waste generation, we show that they are also more energy-efficient.