Abstract: The relationship between black constituency size and congressional support for black interests has two important attributes: magnitude and stability. Although previous research has examined the first characteristic, scant attention has been directed at the second. This article examines the relationship between district racial composition and congressional voting patterns with a particular emphasis on the stability of support across different types of votes and different types of districts. We hypothesize that, among white Democrats, the influence of black constituency size will be less stable in the South, owing in part to this region's more racially divided constituencies. Examining LCCR scores from the 101st through 103rd Congress, we find that this expectation is largely confirmed. We also find that, among Republicans, the impact of black constituency size is most stable—albeit negligible in size—in the South. We conclude by discussing the implications of these findings for the relative merits of “influence districts” and “majority minority” districts.