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Start Over Year 2003 Place Alaska Subject Biology and Ecology
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, and 2006. National Atlas of the United States. This polygon shapefile contains National Wilderness Preservation System areas of 640 acres or more, in the United States, Puerto Rico, and the U.S.... National Atlas of the United States.
2003. United States. Environmental Protection Agency. This polygon shapefile shows Omernik's Level III ecoregions, derived from a 1:7,500,000 map created by J.M. Omernik in 1987 and from refinements of... National Atlas of the United States.
1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, and 2005. United States. Agricultural Research Service. This polygon shapefile portrays the spread, by year, of the Africanized honey bee (AHB) in the United States, Puerto Rico, and the U.S. Virgin Isla... National Atlas of the United States.