Logical consistency: The shapefile is converted to SDC (Smart Data Compression) format using tools in ArcGIS. The SDC data set is then imported into a file geodatabase to verify, validate, and if needed repair the geometry. Horizontal position accuracy: Horizontal positional accuracy is dependent on geographic area. In most areas, accuracy is between 5 and 25 meters (16 and 82 feet). In some areas, accuracy is off by up to several tens of meters (100 feet or more). In the poorest areas, accuracy is off by up to 100 meters (328 feet). Other data details: After processing, the data set is checked for drawing display and number of records and file sizes compared with source materials.
Notes:
U.S. Counties provides boundaries and demographic information for the U.S. counties. The boundaries are consistent with the tract, block group, and state data sets and are effective at county, regional, and state levels. Largest scale when displaying the data: 1:50,000. Publication date: 201112, 201003, 2011, 20111027; ground condition: 2010, 2007. Vector digital data.