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.
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2010. National Geophysical Data Center. This line shapefile shows lines of equal annual change (secular variation) in the vertical component of the total field intensity of the Earth's ma... National Atlas of the United States.
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.
2010. National Geophysical Data Center. This line shapefile shows lines of equal vertical intensity of the Earth's magnetic field, derived from the International Geomagnetic Reference Fie... National Atlas of the United States.
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.).
1989. UNL Libraries Image & Multimedia Collections.
1903. Burgoldt, Paul. Oriented with north to upper right.; Relief shown by contours.; Shows building designations.; From U.S. Congress. Serial set, volume 4647, H.R. Doc... Norris Peters Co., Photo-Litho (Washington, D.C).
1874. Jones, William A. Sheet no. 3. 70 x 42 centimeters Scale 1:1,200,000; 18.94 miles to 1 inch General Map Collection. Reproduced by Military Intelligence Divions, General Staff (Omaha, Neb).
1882. Hals, Carl J. Carroll, Lewis, 1832-1898.
2004. National Atlas of the United States. This polygon shapefile portrays county level data for the fiscal-year-2004 National Fire Plan - Hazardous Fuels Reduction Program. The purpose of t... National Atlas of the United States.