Description: U.S. Airports represents airport boundaries and airport runways within the United States. All airports have a boundary and most have at least one runway.
Description: U.S. National Transportation Atlas Railroads represents a comprehensive database of the nation's railway system at 1:100,000 scale. The data set covers the 48 contiguous States plus the District of Columbia within United States.
Description: U.S. National Atlas Water Feature Lines represents the linear water features (for example, aqueducts, canals, intracoastal waterways, and streams) of the United States.
Description: U.S. National Atlas Water Feature Areas represents the water feature areas (for example, bays, glaciers, lakes, and swamps) of the United States.
Description: 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.