“How does low skilled immigration affect the labour market of natives?” began Joan Monràs from Columbia University at the seminar. “You will be surprised that despite vast studies on wage benefits of migration, there is no consensus amongst researchers!”

He made use of the Mexican Peso Crisis of the mid-1990s that raised net Mexican migration to the US to identify the causal effect of immigration on local labor markets across time, space, skill and age. Time, because more people are expected to settle in a given year; space, since most Mexicans settle in particular areas...