BWx is a legacy US Census Bureau TIGER file format that was used for publishing TIGER data in years past.
The TIGER (Topologically Integrated Geographic Encoding and Referencing) format is used for data sets that store GIS data used by the Census bureau for various mapping purposes. Depending on the vintage, TIGER data provides roads, rivers, lakes, counties, census tracts, census blocks, census block groups and various political and administrative boundaries such as state, county and tribal lands boundaries, cities, congressional districts, school districts, Metropolitan Statistical Areas (MSAs), and ZIP Code Tabulation Areas. for the United States and US territories. TIGER data is in the public domain.
Files in a TIGER data set using BWx format will end in a three letter extension that begins with .BW and ends in a letter or number. The x in the format name BWx refers to the letter or number at the end of the three letter extension. To understand the content of TIGER format files it is important to read Census Bureau publications on the format for the year of release for the data being used.
To import from BWx format:
Choose File-Import from the main menu.
In the Import dialog browse to the location of the BWx files and double-click on the specific .BWx file desired.
Tables and drawings will be created.
The components that are created will often include tables and drawings showing points, lines (called "chains"), areas, points for polygons and points showing the locations of landmarks.
We download and unzip the 1995 TIGER files for the District of Columbia into a folder, which produces a list of BWx files.
We choose File - Import and then use the Import dialog as seen in the first illustration to import the TGR1101.BW1 file.
The BWx dataport imports the above tables and drawings into the project. We right-click on the TGR11001 7 Landmark Features drawing and cnoose New Labels to create a labels component.
In the New Labels dialog we choose the LANAME field to use for the label text. If we do not know TIGER format we could have clicked open the TGR11001 7 table to see right away that the LANAME field contains the names of landmark features.
Next, we open the Map in the project and then drag and drop the new labels layer we have created into the map.
TIGER files contain much data but they require study and some tinker time for effective use. The initial display is a jumble of information.
We can make the display much clearer by using the Style pane to apply colors and formatting and by turning off unnecessary layers.
Shapefiles - Beginning in 2008 the Census Bureau began publishing TIGER data using shapefile format.
Projections - BWx files provide projection information, so drawings will be correctly georegistered.