The US Census Bureau recognizes only urban and rural areas, and assigns specific population requirements to them for classification purposes. An urban area is an area in which the population is greater than 50,000 people, or an area in which the population is between 2,500 and 50,000. A rural area is defined as an area of less than 2,500 people. Suburbs, however, are geographically defined as pockets of populations in the outlying areas of large urban centers. Suburbs are usually classified as urban due to populations of greater than 2,500 and their lack of agricultural focus, though suburbs typically do have open land in the form of parks.