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2010. National Geophysical Data Center. This shapefile contains isodynamic lines (lines of equal total intensity of the Earth's magnetic field), derived from the International Geomagnetic... National Atlas of the United States.
1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, and 1999. Geological Survey (U.S.). This line shapefile portrays the major roads in the United States, Puerto Rico, and the U.S. Virgin Islands. The file was produced by joining the i... Geological Survey (U.S.).
2004. United States. Bureau of Transportation Statistics and United States. Federal Transit Administration. This polyline shapefile depicts the Fixed-Guideway Transit Network, a network database of the nation's fixed-guideway transit systems. Fixed-Guidew... United States. Bureau of Transportation Statistics.
2011. Vanderbilt Engineering Center for Transportation Operations and Research, Waterborne Commerce Statistics Center (U.S.), and United States. Bureau of Transportation Statistics. The National Waterway Network is comprised of a link database and a node database. Links are line strings, which consist of beginning and end point... United States. Bureau of Transportation Statistics.