Established in 1914, the Forest Preserves of Cook County is the oldest and one of the largest forest preserve systems in the nation. With nearly 70,000 acres of public open land—11 percent of the county—we preserve diverse natural ecosystems in the heart of the Chicago region and provide a place for Cook County residents and visitors to explore, learn, play, exercise and restore their spirit. Each year, millions enjoy and study nature, bicycle, hike, fish, picnic, canoe or simply relax.