Import Detailed Geographical Features

Shapefiles are used in geographical information systems to depict individual features such as locations, streets, waterways or lakes, zip code areas, and census blocks. Features are stored in a SHP file as objects and are defined by vector coordinates. Points, lines, or polygons can be included in a shapefile. Topographical information is not included in a .shp file which makes the file faster to process and edit. ESRI (Environmental Systems Research Institute) created the shapefile format in the 1990s to encourage use between ESRI developed products and other GIS applications. Shapefiles are open standard and are compatible with many mapping software programs.

Shapefile Dataset

Shapefiles are a collection of files and require a minimum of three files in the shapefile dataset. Each file has the same name but a different file extension:

blockgroup.shp blockgroup.shx blockgroup.dbf

Shapefile required files include:
.shp vector coordinates; main shape file, each shape is stored as record and has each vertice defined
.shx index file; creates ability to seek backwards and forwards
.dbf attribute file; includes data about each feature, in dBase IV format (database table), there is one record for each feature and they must be in same order as data in .shp file
Shapefiles can also include optional files:
.prj projection format, well-known text file describing coordinate system and type of projection
.sbn and .sbx spatial index of the objects (features) in .shp file
.fbn and .fbx read-only spatial index of the objects (features) for shape files
.ain and .aih attribute index of the active fields in a table
.ixs geocoding index for read-write shapefiles
.mxs geocoding index for read-write shapefiles (ODB format)
.atx attribute index for the .dbf file
.shp.xml metadata
.cpg specifies the code page (only for .dbf) for identifying the character encoding