Important Note to Digital LUCA and BAS Participants


Recently, the U.S. Census Bureau discovered that geographic program participants using the MAF/TIGER Partnership Software or other software (rather than paper maps) to provide road and boundary updates are spatially adjusting large numbers of linear features to match the very detailed level of accuracy in their local GIS.  This is being done by deleting these roads from the less accurate location and then re-adding them in the correct location.  At this time, the Census Bureau is not able to incorporate these changes into our geographic database, the MAF/TIGER database.   

As you review your LUCA or BAS spatial files, the Census Bureau requests that you only provide three types of changes:  (1) Street additions in locations where the Census Bureau is missing them (i.e. new subdivisions), (2) New boundary lines, and (3) Deletions to remove streets found in the Census Bureau data that no longer exist.  We also will accept and process corrections to update street names and feature class codes.

The Census Bureau cannot process spatial adjustments at this time, and we strongly caution you against using your resources to provide these as part of your LUCA or 2008 BAS submission—the emphasis of which should be focused on address and boundary updates.  The MAF/TIGER database is a topologically integrated database that is composed of millions of lines that represent both streets and boundaries.  Therefore, a line in our database may represent a street, is very often the boundary of a uniquely identified census block, and in addition may be the boundary of more than twenty other different types of area, including census tracts, incorporated places, school districts, and state legislative districts.  Because these streets represent many boundaries critical to conducting the decennial census, we cannot further correct the positional accuracy using automated methods without dissolving these underlying relationships.  Instead, they must be adjusted manually in order to maintain the underlying geography critical to our other operations, and our decennial schedule and workload will not permit us to complete this type of manual realignment of linear features in time for the 2010 Census.

We recognize that many local governments have continued to improve the spatial accuracy of their geographic data sets, and we appreciate their willingness and desire to share this more accurate information to improve Census Bureau street data. The Census Bureau is currently developing a plan to continue to incorporate the accurate local government data into the MAF/TIGER database after the 2010 Census.  We look forward to continuing to work with you well into the future on this effort.