U.S. Census TIGER/Line

Driver short name

TIGER

Driver built-in by default

This driver is built-in by default

TIGER/Line file sets are support for read access.

TIGER/Line files are a digital database of geographic features, such as roads, railroads, rivers, lakes, political boundaries, census statistical boundaries, etc. covering the entire United States. The data base contains information about these features such as their location in latitude and longitude, the name, the type of feature, address ranges for most streets, the geographic relationship to other features, and other related information. They are the public product created from the Census Bureau's TIGER (Topologically Integrated Geographic Encoding and Referencing) data base of geographic information. TIGER was developed at the Census Bureau to support the mapping and related geographic activities required by the decennial census and sample survey programs.

Note that the TIGER/Line product does not include census demographic statistics. Those are sold by the Census Bureau in a separate format (not directly supported by FME), but those statistics do relate back to census blocks in TIGER/Line files.

To open a TIGER/Line dataset, select the directory containing one or more sets of data files. The regions are counties, or county equivalents. Each county consists of a series of files with a common basename, and different extensions. For instance, county 1 in state 26 (Michigan) consists of the following file set in Tiger98.

TGR26001.RT1
TGR26001.RT2
TGR26001.RT3
TGR26001.RT4
TGR26001.RT5
TGR26001.RT6
TGR26001.RT7
TGR26001.RT8
TGR26001.RT9
TGR26001.RTA
TGR26001.RTC
TGR26001.RTH
TGR26001.RTI
TGR26001.RTP
TGR26001.RTR
TGR26001.RTS
TGR26001.RTZ

The TIGER/Line coordinate system is hardcoded to NAD83 lat/long degrees. This should be appropriate for all recent years of TIGER/Line production.

There is no update or creation support in the TIGER/Line driver.

The reader was implemented for TIGER/Line 1998 files, but some effort has gone into ensuring compatibility with 1992, 1995, 1997, 1999, 2000, 2002, 2003 and 2004 TIGER/Line products as well. The 2005 products have also been reported to work fine. It is believe that any TIGER/Line product from the 1990's should work with the reader, with the possible loss of some version specific information.

Driver capabilities

Supports Georeferencing

This driver supports georeferencing

Supports VirtualIO

This driver supports virtual I/O operations (/vsimem/, etc.)

Feature Representation

With a few exceptions, a feature is created for each record of a TIGER/Line data file. Each file (i.e. .RT1, .RTA) is translated to an appropriate OGR feature type, with attribute names matching those in the TIGER/Line product manual.

The TIGER/Line RT (record type), and VERSION attributes are generally discarded, but the MODULE attribute is added to each feature. The MODULE attribute contains the basename (eg. TGR26001) of the county module from which the feature originated. For some keys (such as LAND, POLYID, and CENID) this MODULE attribute is needed to make the key unique when the dataset (directory) consists of more than one county of data.

Following is a list of feature types, and their relationship to the TIGER/Line product.

CompleteChain

A CompleteChain is a polyline with an associated TLID (TIGER/Line ID). The CompleteChain features are established from a type 1 record (Complete Chain Basic Data Record), and if available it is associated type 3 record (Complete Chain Geographic Entity Codes). As well, any type 2 records (Complete Chain Shape Coordinates) available are used to fill in intermediate shape points on the arc. The TLID is the primary key, and is unique within the entire national TIGER/Line coverage.

These features always have a line geometry.

AltName

These features are derived from the type 4 record (Index to Alternate Feature Identifiers), and relate a TLID to 1 to 4 alternate feature name numbers (the FEAT attribute) which are kept separately as FeatureIds features. The standard reader pipeline attaches the names from the FeatureIds features as array attributes ALT_FEDIRS{}, ALT_FEDIRP{}, ALT_FENAME{} and ALT_FETYPE{}. The ALT_FENAME{} is a list of feature names associated with the TLID on the AltName feature.

Note that zero, one or more AltName records may exist for a given TLID, and each AltName record can contain between one and four alternate names. Because it is still very difficult to utilize AltName features to relate altername names to CompleteChains, it is anticipated that the standard reader pipeline for TIGER/Line files will be upgraded in the future, resulting in a simplification of alternate names.