Web Mapping Illustrated

Name

TIGER/Line Files

Synopsis

TIGER/Line files are created by the U.S. Census Bureau and cover the entire United States. They are often referred to simply as TIGER files. For more information, see http://www.census.gov/geo/www/tiger/.

File listing

TIGER/Line files are text files and directory-based data sources. For example, one county folder TGR06059 contains several associated files:

    TGR06059.RT1 TGR06059.RT2 TGR06059.RT4 TGR06059.RT5
    TGR06059.RT6 TGR06059.RT7 TGR06059.RT8 TGR06059.RTA
    TGR06059.RTC TGR06059.RTH TGR06059.RTI TGR06059.RTP
    TGR06059.RTR TGR06059.RTS TGR06059.RTT TGR06059.RTZ

Data access/connection method

• TIGER/Line access occurs through OGR.

• The full path to the directory containing the associated files is required in the CONNECTION string. The layer number is added to the CONNECTION string, after the path, separated by a comma: for example., CONNECTION "/tiger/data,0".

• The layer number in the map file is actually the ogrinfo layer number, minus one.

ogrinfo examples

Here's an example that uses ogrinfo on a TIGER directory to retrieve layer numbers:

    > ogrinfo TGR06059 (NOTE that this is a directory) ERROR 4: Tiger Driver doesn't support update. Had to open data source read-only. INFO: Open of 'TGR06059' using driver 'TIGER' successful. 1: CompleteChain (Line String) 2: AltName (None) 3: FeatureIds (None) 4: ZipCodes (None) 5: Landmarks (Point) 6: AreaLandmarks (None) 7: Polygon (None) 8: PolygonCorrections (None) 9: EntityNames (Point) 10: PolygonEconomic (None) 11: IDHistory ...