Drawing on and speaking to literatures in geographic information systems (GIS), queer geography, and queer urban history, we chronicle ethnographically our experience as queer geographers using GIS in an action-research project. We made a map of sites of historical significance in Seattle, Washington, with the Northwest Lesbian and Gay History Museum Project. We detail how queer theory/activism and GIS technologies, in tension with one another, made the map successful, albeit imperfect, via five themes: colliding epistemologies, attempts to represent the unrepresentable, productive pragmatics, the contingencies of facts and truths, and power relations. This article thus answers recent calls in the discipline for joining GIS with social- theoretical geographies, as well as bringing a spatial epistemology to queer urban history, and a cartographic one to queer geography.