In 2021, the US Public Health Service and the US National Park Service (NPS) celebrate a century-long partnership (1921–2021) to protect and promote the health of park visitors, neighboring communities, and the nation. Few know that the impetus and justification for the establishment of NPS are rooted in public health. This paper chronicles the park service’s 100-year commitment to and experience in addressing health protection and promotion through the years and demonstrates how public health has been intrinsic to the purpose and values of the National Park Service from its inception up to the present day. The paper posits a call to action to our nation’s land managers, planners, scientists, political leaders and health officials to build on this tradition to help address some of the most complex and vexing public health issues of the present day, such as the public health implications of a changing climate, and health inequities impacting our nation, and to help parks realize their full potential in contributing to a healthier, happier, more sustainable world.