Search results
Results From The WOW.Com Content Network
In addition, NHGIS has created historical and contemporary cartographic boundary shapefiles compatible with every census, and over 50 million lines of metadata describing the collection. Historical U.S. state and county boundaries are available 1790–present, with smaller geographies available as the U.S. Census Bureau created them.
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 AHCBP documents all boundary changes in states and counties in United States territory, including non-county areas never before compiled or mapped ...
In 2008, data in shapefile format was published. Please note that shapefiles are not topological, therefore may create slivers when comparing TIGER/Line boundaries. This mismatch was not possible when the census TIGER files were available in ASCII format that was topological unlike shapefiles.
Shapefiles : are a data exchange format created by ESRI and one of the most widely used GIS/geodata formats. One "shapefile" usually include four different files : .shp, .shx, .dbf, .prj. First three files must all be present in order to use the data. Each shapefile can hold only one geometry type.
The geographic information available includes orthoimagery (aerial photographs), elevation, geographic names, hydrography, boundaries, transportation, structures and land cover. The National Map is accessible via the Web, as products and services, and as downloadable data. Its uses range from recreation to scientific analysis to emergency ...
[2] Although it is a public database, GADM has a higher spatial resolution than other free databases, [3] and also higher than commercial software such as ArcGIS. [4] Those sources are commonly use to complete data analysis with data visualisation such as data plots, choropleth map, etc. [5] [6]
As noted above under Standards, since 2011 the USNG has been designated by the US Government's National Search and Rescue Committee (NSARC) as the primary coordinate reference system to be used for all land-based search and rescue (SAR) activities in the US. [22] (Latitude and longitude [DMM variant] may be used as the secondary system for land ...
Epi Map is designed to show data from Epi Info 2000 files by relating data fields to SHAPE files containing the geographic boundaries. Shapefiles also can contain data on population or other variables, and can therefore provide numeric data that become part of the display either as numerator or denominator. [1]