Lanfear, K.J. 1993 maps and digital data Reston, Virginia U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?uspop80 A point coverage was created from the 1980 Master Area Reference File (MARF) of the U.S. Census Bureay. Each point represents the center of a census tract, though some tracts were split. A 1980 population is associated with each point. Populations for 1970, 1982, 1984, and 1985 were inferred from county population data. This coverage is intended for applications that need to estimate populations within various polygon sets, or for making "dot maps" to portray population distibution. Related_Spatial_and_Tabular_Data_Sets -- A similar coverage exists for the 1990 Census. The two coverages, however, do not share the same data points. Other_References_Cited -- U.S. Bureau of the Census, 1980. Master Area Reference File for 1980 Census. 19800101 ground condition Complete None planned -127.73757901 -65.45077373 48.19518956 22.9772897 None United States Population Housing inlandWaters None Conterminous United States None 1980 None Only the approximate centers of census tracts are recorded. The point representing a tract can be anywhere within the tract. Some of the larger tracts were split. h2oteam U.S. Geological Survey, Water Resources Div. (WRD) Network Information Products Coordinator for WRD mailing address

12201 Sunrise Valley Drive, MS-439

Reston VA 20192 USA 1-888-275-8747 703-648-5295 h2oteam@usgs.gov 7:30am-4:00pm EST Please contact thru email dgux, 5.4R3.10, AViiON UNIX, ARC/INFO version 7.0.4 Attribute accuracy is described, where present, with each attribute defined in the Entity and Attribute Section. Point features present. 2000000 1980 1.0 Original coverage 1986 1.1 Documentation added. 19930405 Point population data were available from the 1980 census (U.S. Census Bureau, 1980). In general, each point represented the centroid of a census tract, although some tracts were split. The 1980 population was given for each point, along with latitude and longitude. These files were copied from the tapes in ASCII format supplied by the Census Bureau. A conversion program produced one file in the ARC/INFO GENERATE format and another suitable for input of INFO attributes. The point coverage and its point attribute table were generated from these files, and the projection was changed to the standard Albers equal-area projection for the conterminous United States. The original processing for this coverage took place in 1986, and documentation records are incomplete. It is believed that latitude and longitude were given to the nearest minute. State population totals were checked to make sure they were close to other published state population data. The original MARF file had summary entries for counties and states, but these were not included in the point coverage. The total population represented by the points sums to the total population for the conterminous United States. Some of the points in this coverage have zero population. These apparently are legitimate, as the Census could have delineated a tract with no people. The Census Bureau published annual estimates of county populations. Point populations for 1970, 1982, 1984, and 1985 were estimated by proportionally adjusting the 1980 point population data to the change in county population. If, for example, the county population increased 7 percent between 1980 and 1985, then all points in the county were increased 7 percent. The coverage was transferred to a Unix workstation in 1992 and was documented in 1993. The notes on how this coverage was constructed are from the memory. 19930405 Point Point 286607 Albers Conical Equal Area 29.5 45.5 -96 23 0.0 0.0 coordinate pair 1.0 1.0 meters USPOP80.PAT Point attribute table ARC/INFO AREA Degenerate area of point Assigned 0 unspecified unspecified PERIMETER Degenerate perimeter of point Assigned 0 unspecified unspecified USPOP80# Internal feature number Computed Sequential unique positive integer unspecified unspecified USPOP80-ID User-assigned feature number User-defined Integer unspecified unspecified POP70 1970 population U.S. Census Bureau 0- unspecified unspecified POP80 1980 population U.S. Census Bureau 0- unspecified unspecified POP82 1982 population U.S. Census Bureau 0- unspecified unspecified POP84 1984 population U.S. Census Bureau 0- unspecified unspecified POP85 1985 population U.S. Census Bureau 0- unspecified unspecified WORKB Working variable n/a No restrictions unspecified unspecified FIPS County code FIPS 0-56999 unspecified unspecified HUC Hydrologic Unit code FIPS 01000000-21999999 unspecified unspecified HUC4 Subregion FIPS 0100-1899 unspecified unspecified HUC6 Accounting unit FIPS 010000-189999 unspecified unspecified HUC2 Region FIPS 01-18 unspecified unspecified FIPSHUC County-Hydrologic Unit code n/a 0100101000000-5699918999999 unspecified unspecified A county code and a hydrologic unit code are associated with each point. The population for 1980 is from the MARF records. Populations for 1970, 1982, 1984, and 1985 are estimated from county data. U.S. Geological Survey Ask USGS - Water Webserver Team mailing

445 National Center

Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+uspop80 Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Export Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/uspop80.e00.gz SDTS Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/uspop80.sdts.tgz None. This dataset is provided by USGS as a public service. 20041108 U.S. Geological Survey Ask USGS -- Water Webserver Team mailing

445 National Center

Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+uspop80 FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998