1) Areas with a population of 50,000 or more, at a minimum, encompass an entire urbanized area in a state, as designated by the U.S. Bureau of the Census. The Federal Highway Administration (FHWA) approved, adjusted urbanized area boundaries include the census defined urbanized areas plus transportation centers, shopping centers, major places of employment, satellite communities, and other major trip generators near the edge of the urbanized area, including those expected to be in place shortly. 2) An approximate classification of sample households as belonging to an urbanized area or not. Those classified as belong to an urbanized area were either in a central city of a Metropolitan Statistical Area (MSA), or in a MSA but outside the central city, and within a zip code area with a population density of at least 500 people per square mile in 1990.
(FHWA2) (FHWA3)