Parks and recreation departments and public health organizations both work to improve the well-being of their communities. Measuring residential proximity to parks could be a specific area of shared interest, given that proximity to parks is needed for walking access, and the use of parks is, in turn, associated with many physical, social, and mental health benefits. The CDC's publicly available National Environmental Public Health Tracking Network (NEPHTN) Access to Parks Indicator (API) focuses on one major component of access, residential proximity to parks. The API uses a commercial parks database and U.S. Census data to estimate the number and percentage of individuals in the U.S. that live within a half-mile of a park boundary, a measure commonly used to represent park proximity. The API is calculated at the state and county levels and is available for all states and counties in the U.S. Using estimates from the API, we examined the distribution of residential proximity to parks by geography and race/ethnicity. Additionally, we evaluated differences in park proximity by rural/urban status of counties. In 2010, 39% of the total U.S. population lived within a half-mile of a park. This percentage varied widely between states, ranging from 9% in West Virginia to 67% in Hawaii and 88% in the District of Columbia (DC). Park proximity was lowest among non-Hispanic whites (34.2%) and highest among individuals belonging to the non-Hispanic other race category (52.0%). Metropolitan counties had the highest percentage of residents living within a half-mile of a park (43.3%); the percentage was lower in non-metropolitan counties adjacent to a metropolitan county (15.0%) and non-metropolitan counties not adjacent to a metropolitan county (18.5%). Park proximity was higher in metropolitan counties with a larger population size and in non-metropolitan counties with a higher degree of urbanization. The NEPHTN Access to Parks Indicator provides an opportunity to understand park proximity in counties and states throughout the U.S., including identifying disparities that may exist between population subgroups and comparing geographic areas. Parks and recreational professionals can use this information to compare their county or state to other geographic areas and, in combination with local data on parks within their jurisdiction, inform decisions to improve the distribution of parks and the well-being of their communities.