This paper, first, provides an analysis of contemporary anti‐immigration activism in the United States, situating it historically and theoretically through an examination of nativism and vigilantism. Second, it merges insights from political process theory and structured ignorance theory to develop an historical account of three key preconditions that set the stage for and accelerated contemporary anti‐immigration activism. In so doing this paper addresses fundamental empirical and theoretical gaps in political process theory and demonstrates how structured ignorance theory can help us better understand how shifting structural conditions promoted contemporary anti‐immigration mobilization by generating perceptions conducive to conservative activism.