Sustainability is frequently defined as the need to place equal emphasis on three societal goals: economic prosperity, environment, and social equity. This “triple bottom line” (TBL) framework is embraced by practitioners in both corporate and government settings. Within agriculture, the horse-racing industry and its breeding component are an interesting case study for the TBL approach to local development. The sector is to some extent a “knowledge industry”, agglomerating in relatively few regions worldwide. In the USA, choices made by breeders or owners are likely affected by sudden changes in specific state policies, especially those related to gambling. Both of these unusual conditions—for agriculture at least—have been playing out against a background of national decline in the number of registered racehorse breeding stock. This study traces changes, between 1995 and 2017, in the geographic distribution of registered Thoroughbred and Standardbred stallions. We find that isolated, scattered registered stallions have largely disappeared, strengthening one or more core states (or counties) that had an initially high percentage of stallions. The gainers and losers among previously core regions appear to be heavily influenced by state-level policies. It follows that such policies can influence the conservation of agricultural landscapes as well as racing revenues.