Counties in the United States are administrative divisions within states, serving as important units for local government. Each state has its own system of counties, which can vary in number and size. Counties typically handle local services such as law enforcement, education, and infrastructure maintenance. There are over 3,000 counties across the country, with Los Angeles County in California being the most populous. Counties can also include cities, towns, and rural areas, providing a framework for governance and community organization. They play a crucial role in the political and social structure of the U.S.