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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.
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.
1851. Center for Spatial and Textual Analysis. This layer is a georeferenced raster image of a map of the United States, Canada, Mexico, Central America, and the West India Islands, with portion... Stanford Digital Repository.
1947, 1948, 1949, 1950, 1951, 1952, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 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, 1999, and 2000. Schultz, Kenneth A. This polygon shapefile represents areas that were the subject of interstate territorial disputes between 1947 and 2000. The disputed areas referenc... Stanford Digital Repository.
2004. Instituto Nacional de Estadística, Geografía e Informática (Mexico), Canada Centre for Mapping, and Geological Survey (U.S.). This line shapefile shows bathymetric contours with depth in metres for ocean areas covered by the extent of the North American Atlas project. Isob... Canada Centre for Mapping, Instituto Nacional de Estadística, Geografía e Informática (Mexico), and Geological Survey (U.S.).
2004. Instituto Nacional de Estadística, Geografía e Informática (Mexico), Canada Centre for Mapping, and Geological Survey (U.S.). This polygon shapefile contains bathymetric data with depth in metres for ocean areas covered by the extent of the North American Atlas project. Is... Canada Centre for Mapping, Instituto Nacional de Estadística, Geografía e Informática (Mexico), and Geological Survey (U.S.).
1830, 1831, 1832, 1833, 1834, 1835, 1836, 1837, 1838, 1839, 1840, 1841, 1842, 1843, 1844, 1845, 1846, 1847, 1848, 1849, 1850, 1851, 1852, 1853, 1854, 1855, 1856, 1857, 1858, 1859, 1860, 1861, 1862, 1863, 1864, 1865, 1866, 1867, 1868, 1869, 1870, 1871, 1872, 1873, 1874, 1875, 1876, 1877, 1878, 1879, 1880, 1881, 1882, 1883, 1884, 1885, 1886, 1887, 1888, 1889, 1890, 1891, 1892, 1893, 1894, 1895, 1896, 1897, 1898, 1899, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1921, 1922, 1923, 1924, 1925, 1926, 1927, 1928, 1929, 1930, 1931, 1932, 1933, 1934, 1935, 1936, 1937, 1938, 1939, 1940, 1941, 1942, 1943, 1944, 1945, 1946, 1947, 1948, 1949, 1950, 1951, 1952, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 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, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, and 2008. National Atlas of the United States. This poygon shapefile portrays the distributions of United States and Canadian bat species during the past 100-150 years (1830-2009). The specimen ... National Atlas of the United States.
1599. Rumsey, David, 1944-, Ptolemy, Claudius, and Ruscelli, Girolamo. This layer is a georeferenced image of an engraved map of New Spain from 1599. Showing the southern United States, including Texas and Florida and ... Cartography Associates.