In the past decade, the Home Owners’ Loan Corporation’s (HOLC) so-called ‘redlining’ maps have gone from a niche corner of urban historical scholarship to the centre of mainstream narratives about racism in the United States. In this paper, I map this journey and trace the contours of the ongoing debates that have emerged, identifying two competing camps I call ‘HOLC Culpablism’ and ‘HOLC Scepticism’. Finding these perspectives to have run up against their self-imposed limitations, I outline a research agenda that breaks from the debate’s narrow confines by envisioning HOLC’s mapping materials anew. My proposed approach recasts the maps and their accompanying field notes as windows into the governing racial–spatial ideology of 20th-century US real estate capital. In doing so, it invites researchers to reimagine the map grades as dynamic categories reflecting a particular spatiotemporal conception of value that is highly contingent on an area’s estimated racial trajectory. This reformulation, I argue, not only opens new possibilities for studying the HOLC mapping programme but suggests that the power of these maps has almost certainly been underestimated.