This paper studies the impact of U.S. restrictions on skilled immigration on the Canadian economy and on the welfare of American workers. We leverage a unique quasi-natural experiment given by an abrupt and significant policy change that occurred in 2017 within the H-1B program. We use visa application data for the U.S. and Canada, and a comprehensive collection of Canadian administrative databases to document novel facts. We show that increasing H-1B denial rates increased skilled immigration into Canada and increased the production and exports of Canadian firms and the employment of Canadian workers. Finally, we incorporate migration policy in a model of international trade and assess the aggregate effects of this U.S. immigration policy change. We also use the model to analytically show how immigration restrictions in the U.S. indirectly impact the welfare of natives by increasing immigration in other countries.