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2014. National Atlas of the United States. This map layer portrays the major roads in the United States, Puerto Rico, and the U.S. Virgin Islands. The file was produced by joining the indivi... National Atlas of the United States.
2014. National Atlas of the United States. This line shapefile includes Global Map data showing streams in the United States, Puerto Rico, and the U.S. Virgin Islands. The data are a modifie... National Atlas of the United States.
2011. United States. Bureau of the Census. Geography Division and United States. Bureau of Transportation Statistics. This polyline shapefile depicts hydro coverages that were created using TIGER/Line 2000 shapefile data gathered from ESRI's Geography Network. The ... United States. Bureau of Transportation Statistics.
2010. National Geophysical Data Center. This map layer shows isogonic lines (lines of constant declination of the Earth's magnetic field), derived from the International Geomagnetic Refer... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal horizontal intensity of the Earth's magnetic field, derived from the International Geomagnetic Reference F... National Atlas of the United States.
2010. National Geophysical Data Center. This shapefile shows isoclinic lines (lines of constant inclination of the Earth's magnetic field), derived from the International Geomagnetic Refe... National Atlas of the United States.
2010. National Geophysical Data Center. This map layer shows isoporic lines (lines of equal annual change, or secular variation, in the declination of the Earth's magnetic field), derived... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation) in the horizontal component of the total field intensity of the Earth's ... National Atlas of the United States.
2010. National Geophysical Data Center. This shapefile shows lines of equal annual change (secular variation) in the inclination of the Earth's magnetic field, derived from the Internatio... National Atlas of the United States.
2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation), in the total field intensity of the Earth's magnetic field, derived fro... National Atlas of the United States.