Group Size and Social Interaction: a Canada-US Comparison of Interracial Marriage

While black-white intermarriage is uncommon in the United States, blacks in Canada are just as likely to marry whites as to marry blacks. Asians, in contrast, are more likely to marry whites in the US than in Canada. We test the claim that high rates of interracial marriage are indicative of high levels of social integration against Peter Blau’s ‘macrostructural’ thesis that relative group size is the key to explaining differences in intermarriage rates across marriage markets. Using micro-data drawn from the American Community Survey and the Canadian Census, we demonstrate that the relative size of racial groups accounts for over two-thirds of the US-Canada difference in black-white unions and largely explains the cross-country difference in Asian-white unions. Under broadly similar social and economic conditions, a large enough difference in relative group size can become the predominant determinant of group differences in the prevalence of interracial unions.