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TIGER data published through February 2007 (2006 Second Edition) were in a custom text-based format formally known as TIGER/Line files. In 2008, data in shapefile format was published. Please note that shapefiles are not topological, therefore may create slivers when comparing TIGER/Line boundaries.
U.S. Gazetteer, TIGER/Line shapefiles, census data. National Historical Geographic Information System: NHGIS provides free of charge, aggregate census data and GIS-compatible boundary files for the United States between 1790 and 2012. Atlas of Historical County Boundaries Project (AHCBP)
The shapefile format is a geospatial vector data format for geographic information system (GIS) software.It is developed and regulated by Esri as a mostly open specification for data interoperability among Esri and other GIS software products. [1]
This was most common from the 1970s through the early 1990s, because GIS software developers had to invent their own geometry data structures, but incorporated existing relational database file formats for the attributes. For example, the Esri Shapefile format includes the .dbf file from the DOS dBase software.
OpenStreetMap (abbreviated OSM) is a free, open map database updated and maintained by a community of volunteers via open collaboration. [4] Contributors collect data from surveys, trace from aerial photo imagery or satellite imagery, and import from other freely licensed geodata sources.
GIS seems to provide many advantages in teaching geography because it allows for analysis based on real geographic data and also helps raise research questions from teachers and students in the classroom. It also contributes to improvement in learning by developing spatial and geographical thinking and, in many cases, student motivation.
For example, the fact that two regions overlap or that one contains the other are examples of topological relationships. It is thus the application of the mathematics of topology to GIS, and is distinct from, but complementary to the many aspects of geographic information that are based on quantitative spatial measurements through coordinate ...
Sergeant Chris D. Washington checking his Topographic map during a morning deer hunt in Kilgore, Texas A topographic map of Stowe, Vermont with contour lines Part of the same map in a perspective shaded relief view illustrating how the contour lines follow the terrain Sheet #535 (2013 version; second digital edition) of MTN50 Spanish National Topographic map series, covering Algete town (near ...