| Terms | Definitions |
|---|
| U.S. Coastal District | All United States waters subject to the tide, waters of the Great Lakes and Lake Champlain, specified ports and harbors on inland rivers, waters of the contiguous zone, other waters of the high seas subject to the National Contingency Plan, and the land surface or land substrate, ground waters, and ambient air proximal to those waters. The term coastal zone delineates an area of federal responsibility for response action. Precise boundaries are determined by agreements between the Environmental Protection Agency (EPA) and the U.S. Coast Guard (USCG), and are identified in Federal Regional Contingency Plans and Area Contingency Plans. There are nine U.S. coastal regions: North Atlantic, South Atlantic, Gulf, California, Pacific Northwest, Great Lakes, Hawaii, Alaska, and Puerto Rico/Virgin Islands. ( Foreign Traffic Vessel Entrances and Clearances ) |
| USCG | U.S. Coast Guard ( National Ferry Database ) |
| USPS Codes | United States Postal Service (USPS) codes for States are used in all American Travel Survey (ATS) data products. The codes are two-character alphabetic abbreviations. These codes are the same as the FIPS two-character alphabetic abbreviations. ( American Travel Survey ) |
| UZA | Urbanized Area; 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. ( National Transit Database ) |
| Underride/Override | Underride generally occurs as the result of a collision between vehicles of substantially different size. Underride happens when all or part of the vehicle goes underneath the chassis of another vehicle during a collision. Override happens when another vehicle goes underneath the chassis of the vehicle in question during a collision. ( Trucks Involved Fatal Accidents ) |
| Unknown | Data either not available or not known. ( Fatality Analysis Reporting System ) |
| Unlinked Passenger Trips | The number of passengers who board public transportation vehicles. Passengers are counted each time they board vehicles no matter how many vehicles they use to travel from their origin to their destination. ( National Transit Database ) |
| Urban | Includes all areas of a state inside of the Federal Highway Administration (FHWA) approved adjusted census boundaries of small urban and urbanized areas. ( Vehicle Miles Traveled, Highway Perfomance Monitoring System ) |
| Urban Collectors | Those public roads that are functionally classified as a part of the urban collector system as described in volume 20, appendix 12, Highway Planning Program Manual. ( Vehicle Miles Traveled ) |
| Urbanized Area | An approximate classification of sample households as belonging to an urbanized area. Those classified as belonging to an urbanized area were either in a central city of an 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. ( Nationwide Personal Transportation Survey ) |
| Densely settled territory that contains 50,000 or more people. ( Census Transportation Planning Package ) |
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