National Public Lands Day (NPLD) is observed in the United States on every fourth Saturday of September. This annual event focuses on the volunteer conservation of public lands, which include parks, forests, and wildlife management areas. NPLD began in 1994 with 700 volunteers participating at three public land sites, and by 2014, the initiative had grown to approximately 175,000 volunteers across more than 2,000 sites in the U.S. and Puerto Rico. Volunteers engage in various activities such as collecting invasive plants, building and maintaining trails, planting trees and shrubs, and removing trash from public lands. The event is supported by federal agencies, state, regional, and local governments, as well as non-profit organizations, all working together to promote the care and education of citizens about natural resources and the environment.