Urban Areas (ESRI) --
U.S. Census Urbanized Areas, 2003 (1:300,000)

U.S. Census Urbanized Areas represents the Census 2000 Urbanized Areas (UA) and Urban Clusters (UC). A UA consists of contiguous, densely settled census block groups (BGs) and census blocks that meet minimum population density requirements (1000ppsm /500ppsm), along with adjacent densely settled census blocks that together encompass a population of at least 50,000 people. A UC consists of contiguous, densely settled census BGs and census blocks that meet minimum population density requirements, along with adjacent densely settled census blocks that together encompass a population of at least 2,500 people, but fewer than 50,000 people. The dataset covers the 50 States plus the District of Columbia within United States. U.S. Census Urbanized Areas provides information about the locations, names, and urban codes of urbanized areas primarily for national planning applications. This layer is used as a background layer on the LakeRim site, and is available from Environmental Research Systems, Incorporated (ESRI).