This article builds on settler and domestic colonial histories and theories to advance our understanding of urban changes in segregated, disinvested, U.S. Rust Belt cities. While many major cities have rebounded in population and experienced gentrification since the mid-twentieth century, many Rust Belt cities have continued to decline. The resulting conditions call for new theories to describe their changes, trajectories, and the impacts for majority poor Black populations. We construct a Binocular Colonial Lens: an analytic framework that superimposes shared conceptual descriptions and theoretical explanations of settler and domestic colonialisms. With this lens, we can elucidate the practices of erasure that are deployed throughout colonized communities and focus them on phenomena associated with urban decline and revitalization. While some urban scholarship has used metaphors and language of settler colonialism to describe gentrification, most of these works at best reflect the salience of settler ideology, and at worst reinforce Indigenous erasure. Foregrounding shared conditions of colonization and conquest in the United States, we train this Binocular Colonial Lens on Detroit, which reveals myriad urban processes like ghettoization, urban renewal, suburbanization, and gentrification as ongoing colonization, wherein domestically colonized populations are subject to numerous forms of erasure at the behest of the settler state and toward the advancement of settler society. This lens advances urban theory by expanding the depth of our analyses of urban changes, and scaffolds connections with other axes of racialized inequality by revealing shared tools of erasure operative in, for example, mass incarceration and environmental injustices.