Windsor in Ontario, Canada and Detroit in Michigan, USA are Great Lakes border cities on the Detroit River that have a long history of water pollution. Public outcry over water pollution in the 1960s led to the enactment of environmental laws starting in the early 1970s. As these laws were implemented and water quality improved, citizens started calling for improved public access to the river, including establishing linked riverfront greenways. This paper presents a case study of greenway development in these border cities based on indicator reporting to comprehensively assess ecosystem health. Findings show that waterfront greenways were catalyzed by cleanup of the Detroit River. As greenway systems expanded on both sides of the border, greenway stakeholders began to envision cross-border greenway connections that would stimulate ecotourism, help encourage healthy lifestyles, and enhance quality of life in southwest Ontario and southeast Michigan. Recommended next steps include investing in greenway capacity building, identifying and testing creative financing options for greenways, formalizing institutional arrangements between Canada and the United States for a binational greenway network, and strengthening cross-border greenway connections by reestablishing a cross-border ferry, offering free access to the tunnel bus on weekends for cyclists, and hosting Windsor-Detroit open streets' events. Robust transboundary greenway partnerships are critical to realizing the full potential of cross border greenway systems, including expanding outdoor recreation and ecotourism, conserving natural resources, and inspiring a stewardship ethic for shared ecosystems.