Cook County is located in the state of Illinois and is the second-most populous county in the United States. It encompasses the city of Chicago, which is the county seat and a major cultural and economic hub. The county is known for its diverse communities, rich history, and significant contributions to arts and industry. The county covers an area of approximately 1,635 square miles and includes numerous suburbs and smaller towns. Cook County is home to various parks, forests, and recreational areas, providing residents and visitors with opportunities for outdoor activities. It also hosts several important institutions, including the Cook County Hospital and the Cook County Jail.