Formal historic preservation is a professional and sanctioned approach to the conservation of our historically significant built cultural heritage. Postindustrial landscapes are, by definition, functionally and materially obsolete, and in many cases derelict and decaying. While they hold historical significance, these sites are often not widely perceived as valuable contributors to our heritage. Yet these landscapes persist. We argue that the material persistence of these features is the result of generally unrecognized processes of informal material conservation. In this paper, we outline a new framework, vernacular preservation , an ontology for heritage professionals to use in considering how to approach and recognize nonformal interventions that result in the protection of heritage resources. Here, we use the postindustrial landscape of Michigan's Keweenaw Peninsula—a former copper-mining district—to illustrate how vernacular preservation differs from formal historic preservation, reviewing the process of vernacular preservation and how it is activated in practice. Vernacular preservation constitutes perhaps the most traditional, common, and widespread mechanism of material conservation of the historical built environment yet has been largely invisible, little discussed, and undertheorized by the heritage preservation community. Understanding this preservation process begins by acknowledging its existence and by extending the heritage dialogue to include these underrepresented historical properties and their important role in defining postindustrial landscapes. We conclude the paper with a discussion on how this novel approach to thinking about preservation extends broadly to the field and should be given greater attention.