Scholarly work on “shrinking” cities grew following the 2010 Census, resulting in a diverse body of popular and academic literature. However, this has not produced a widely accepted definition of the “shrinking city”. We analyze definitions used in a sample of papers on U.S. shrinking cities, and propose an empirically justified definition that reflects the shrinking cities research agenda and is easily operationalized. We demonstrate that our resulting universe of 83 cities represents the places studied in the literature and provides a starting point for future research. We hope to draw scholars to a shared understanding of this pressing topic.