Matching theory suggests that a demographic shock that shifts marriage market conditions should affect all men and women, not just the group impacted by the shock. This paper uses data on cross-border marriages in East Asia to evaluate these equilibrium effects. It exploits two events that dramatically changed the volume of marriage migration between Vietnam and Taiwan: the rapid emergence of matchmaking firms in the late 1990s, and a tightening of entry visas in Taiwan in 2004. I show that the number of marriage migrants significantly affects the matching patterns and intra-household allocations of local people in both countries. For instance, when marriage migration becomes easier and thus more common, a larger number of less well-educated Vietnamese women emigrate; and those who stay in Vietnam benefit from more control over household expenditures. This purely equilibrium phenomenon takes place even though only a small percentage of Vietnamese women of marriageable age emigrate. My results suggest that changes in trade and immigration policies can have far-reaching implications on marital outcomes and women's bargaining power.