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The 2014 cartographic boundary shapefiles are simplified representations of selected geographic areas from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). These boundary files are specifically designed for small-scale thematic mapping. When possible, generalization is performed with the intent to maintain the hierarchical relationships among geographies and to maintain the alignment of geographies within a file set for a given year. Geographic areas may not align with the same areas from another year. Some geographies are available as nation-based files while others are available only as state-based files. States and equivalent entities are the primary governmental divisions of the United States. In addition to the fifty States, the Census Bureau treats the District of Columbia, Puerto Rico, and each of the Island Areas (American Samoa, the Commonwealth of the Northern Mariana Islands, Guam, and the U.S. Virgin Islands) as the statistical equivalents of States for the purpose of data presentation.
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This map presents the terrestrial ecosystems in the conterminous United States, and was developed as part of the United States Geological Survey’s (USGS) effort to model the distribution of terrestrial ecosystems using the geospatial mapping methodology that was developed from a deductive, biophysical stratification approach to delineate ecosystems by their major structural elements (Sayre and others, 2009). Each major structural component of ecosystems (land surface forms, surficial lithology, bioclimates, topographic moisture potential, and so forth) was modeled and then spatially combined to produce a new map of biophysical settings, termed ecosystem structural footprints. These ecosystem structure units characterize the abiotic (physical) potential of the environment. As the final step in this process, the unique structural footprints are aggregated into the terrestrial ecosystems classification that was developed by NatureServe (Comer and others, 2003). Additional information and access to this data is available at http://rmgsc.cr.usgs.gov/ecosystems/.
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The U.S. Geological Survey (USGS) modeled the distribution of terrestrial ecosystems for the contiguous United States using a standardized, deductive approach to associate unique physical environments with ecological systems characterized in NatureServe's Ecological Systems of the United States classification (Comer et al., 2003). This approach was first developed for South America (Sayre et al., 2008) and is now being implemented globally (Sayre et al., 2007). Unique physical environments were delineated from a massive biophysical stratification of the nation into the major structural components of ecosystems: biogeographic regions (Cress et al., 2008c), land surface forms (Cress et al., 2008a), surficial lithology (Cress et al., 2008d), and topographic moisture potential (Cress et al., 2008b). Each of these structural components was mapped for the contiguous United States and then spatially combined to produce ecosystem structural footprints which represented unique abiotic (physical) environments. Among 49,168 unique structural footprint classes, 13,482 classes which met a minimum pixel count threshold (20,000 pixels) were aggregated into 432 NatureServe ecosystems through semi-automated labeling process using rule set formulations for attribution of each ecosystem.
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The U.S. Geological Survey (USGS) has generated a new classification and map of the lithology of surficial materials for the contiguous United States. This was developed as part of an effort to map standardized, terrestrial ecosystem distributions for the nation using a classification developed by NatureServe (Comer and others, 2003). This ecosystem mapping methodology, which delineates ecosystems by mapping and integrating their major structural components, was first developed for South America (Sayre and others, 2008) and is now being implemented globally (Sayre and others, 2007). Surficial lithology strongly influences the differentiation and distribution of terrestrial ecosystems, and is one of the key input layers in the ecosystem delineation process. These surficial lithology classes were derived from the USGS map "Surficial Materials in the Conterminous United States", which was based on texture, internal structure, thickness and environment of deposition or formation of materials (Soller and Reheis, 2004). This original map was produced from a compilation of regional surficial and bedrock geology source maps using broadly defined common map units for the purpose of providing an overview of the existing data and knowledge (Soller and Reheis 2004). For the national terrestrial ecosystem mapping effort, the original 28 lithology classes were reclassified into a set of 18 lithologies that typically control or influence the distribution of vegetation types (Kruckeberg, 2002).
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Shapefile created using satellite-derived land cover data and shaded relief presented with a light, natural palette suitable for making thematic and reference maps. Natural Earth I is available with ocean bottom data, or without. File size: 10,800 x 5,400 pixels. Coloring based on land cover.
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The U.S. Geological Survey (USGS) has generated and mapped isobioclimate classes for the contiguous United States. These isobioclimate classes were created as part of an effort to map standardized, terrestrial ecosystems for the nation using a classification developed by NatureServe (Comer and others, 2003). Ecosystem distributions were modeled using a biophysical stratification approach developed for South America (Sayre and others, 2008) and now being implemented globally (Sayre and others, 2007). Bioclimate regimes strongly influence the differentiation and distribution of terrestrial ecosystems, and are one of the key input layers in the ecosystem delineation process. The Rivas-Martínez methodology used to produce these classes was developed from a consideration of bioclimatology and its relationship to phytogeography (Rivas-Martínez, 2004; Rivas-Martínez and others, 1999, 2004). This approach develops a number of bioclimatic indices calculated from a variety of data on temperature and precipitation (e.g. average temperature of the coldest month, total precipitation of the warmest four-month period, a continentality index and a thermicity index). Daymet data, which was developed from 18-year (1980-1997) climatological records and is available at a spatial resolution of 1 kilometer, was used as the source data for these indices (Thornton, 1997). Once calculated the values of these indices are compared to established thresholds for the differentiation of thermotypic (warm/cold gradients) and ombrotypic (wet/dry gradients) regions, and the results are used in sets of decision rules to identify classes. The classification is implemented in four levels: macrobioclimates, bioclimates, thermotypes (thermoclimatic belts) and ombrotypes (ombroclimatic belts). The final isobioclimates dataset represents areas of the 127 unique thermotype-ombrotype combinations that were mapped for the contiguous United States.
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Shapefile created using relief shading and hypsography derived from modified SRTM Plus elevation data at 1km resolution. Modifications include patching the eastern Himalayas and southern Andes with better elevation data from Viewfinder Panoramas. Daniel Huffman, University of Wisconsin, Madison, created the regionally equalized hypsography that forms the foundation of Gray Earth. Two sizes are offered: large size at 21,600 x 10,800 pixels and medium at 16,200 x 8,100. The aim of Gray Earth is mapmakers working in black and white and those seeking a neutral terrain base map on which to overlay vibrant colors representing thematic data. Against the gray terrain, colors will pop. The terrain combines shaded relief and hypsography in even proportions and with just the right amount of contrast; Earth’s landforms are clear to see yet the terrain is light enough so as not to interfere with overprinting type and lines. Gray Earth is also highly malleable in Photoshop. A simple levels adjustment can make the terrain lighter or darker depending on your map design intent.
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The 2014 cartographic boundary shapefiles are simplified representations of selected geographic areas from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). These boundary files are specifically designed for small-scale thematic mapping. When possible, generalization is performed with the intent to maintain the hierarchical relationships among geographies and to maintain the alignment of geographies within a file set for a given year. Geographic areas may not align with the same areas from another year. Some geographies are available as nation-based files while others are available only as state-based files. The American Indian/Alaska Native/Native Hawaiian (AIANNH) Areas cartographic boundary file includes generalized versions of the following legal entities: federally recognized American Indian reservations and off-reservation trust land areas, state-recognized American Indian reservations, and Hawaiian home lands (HHLs). The statistical entities included are Alaska Native village statistical areas (ANVSAs), Oklahoma tribal statistical areas (OTSAs), tribal designated statistical areas (TDSAs), and state designated tribal statistical areas (SDTSAs). Joint use areas are also included in this shapefile refer to areas that are administered jointly and/or claimed by two or more American Indian tribes. The Census Bureau designates both legal and statistical joint use areas as unique geographic entities for the purpose of presenting statistical data. Note that tribal subdivisions and Alaska Native Regional Corporations (ANRCs) are additional types of American Indian/Alaska Native areas stored by the Census Bureau, but are displayed in separate files because of how they fall within the Census Bureau's geographic hierarchy.
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The 2013 cartographic boundary shapefiles are simplified representations of selected geographic areas from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). These boundary files are specifically designed for small-scale thematic mapping. When possible generalization is performed with the intent to maintain the hierarchical relationships among geographies and to maintain the alignment of geographies within a file set for a given year. Geographic areas may not align with the same areas from another year. Some geographies are available as nation-based shapefiles while others are available only as state-based files.
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Shapefile created using generalized single-line drainages including optional lake centerlines data from the 10 million rivers. The 50 million rivers primarily derive from World Data Bank 2. Double line rivers in WDB2 were digitized to created single line drainages. All rivers received manual smoothing and position adjustments to fit shaded relief generated from SRTM Plus elevation data, which is more recent and (presumably) more accurate. Lake centerlines obtained by manually drawing connecting segments in reservoirs. When available, Admin 0 and 1 political boundaries in reservoirs serve as the lake centerlines. Ranked by relative importance. Includes name and line width attributes for creating tapered drainages.