1999. Patuxent Wildlife Research Center. This line shapefile portrays the current routes used for conducting Breeding Bird Surveys in the lower 48 States. This layer is part of the 1997-20... National Atlas of the United States.
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1999. University of Minnesota. Institute on the Environment. Land used for agricultural production presents a tradeoff to society. On one hand, agricultural lands provide essential food, feed, fiber, and incr... University of Minnesota. Institute on the Environment.
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.).
1999. National Geophysical and Solar-Terrestrial Data Center. This map shows light sources from human settlements around the world observed during 1999. The Defense Meteorological Satellite Program (DMSP) Oper... National Geophysical and Solar-Terrestrial Data Center.