Public lands are typically established in recognition of their unique ecological value, yet both ecological and social values of public lands change over time, along with human distribution and land use. These transformations are evident even in developed countries with long histories of public land management, such as the United States. The 20th Century saw dramatic changes in the American population, in distribution and in racial and ethnic diversity, leading to new challenges and new roles for public lands. Our goal with this paper is to review changing demographics and implications for terrestrial protected areas in the U.S. We overview the fundamentals of population change and data, review past trends in population change and housing growth and their impacts on public lands, and then analyze the most recent decade of demographic change (2000-2010) relative to public lands. Discussions of demographic change and public lands commonly focus on the rural West, but we show that the South is also experiencing substantial change in rural areas with public lands, including Hispanic population growth. We identify those places, rural and urban, where demographic change (2000-2010), including diversification and housing growth, coincide with public lands. Understanding the current trends and long-term demographic context for recent changes in populations can help land managers and conservation scientists mitigate the effects of residential development near public lands, serve a more diverse population, and anticipate future population changes.