Unions and the rights of migrants in the long run

We use historical data on union density and new historical data on policies toward migrants to study the long-run relationship between the strength of trade unions and the social and economic rights of migrants in the Global North. In countries with strong trade unions, there was, for a long time, a widening distance between the rights of migrants and the rights of citizens, probably because the rights of citizens expanded sooner and more quickly than the rights of migrants. Over time, however, the differences between countries with strong and weak unions have diminished, and in more recent years, the 'rights gap' between citizens and migrants has in fact been smaller in countries with strong unions than in countries with weak unions.