Reservation policies and equity in national park access.

National parks are experiencing unprecedented demand. High use strains infrastructure, damages ecosystems and reduces visitor enjoyment. To sustainably manage visitation, many parks now require reservations, raising concerns about equity. We quantify the effects of two reservation system features, advance purchase windows and competition for permits, on visitor income at seven national parks. Both effects disproportionately favor higher-income users. In the most competitive day-ahead and advance markets, reservation holders come from zip codes with 3-5% higher median household income. Extending the advance purchase window to six months shifts reservations toward users residing in zip codes with 5% higher income. Robustness checks imply individual effects of the same direction. This underscores a key challenge for park managers: designing reservation systems that protect resources while ensuring broad access. Without attention to distributional impacts, efforts to control crowding risk exacerbating income-based disparities in who can visit and enjoy the nation's public lands.