Supporting the National Spatial Data Infrastructure at the United States Census Bureau

The Framework Layers
Seven initial data themes of common national significance and coverage were determined necessary to build the foundation for the NSDI.The layers are:

cadastral
orthoimagery
geodetic control
elevation and bathymetry
hydrogragraphy
transportation
governmental units

The U.S.Census Bureau's role in the Framework
Subcommittees of the FGDC were created to define the content and standards for each framework layer.Each layer contains more than just the seven themes listed above for the subcommittees to define.Each subcommittee is lead by the federal agency with which the main responsibility for that theme lies.The U.S.Census Bureau leads the Cultural and Demographic Data Subcommittee.The governmental units layer is within the purview of the Cultural and Demographic Data Subcommittee data.

The U.S.Census Bureau is considered to be the national repository of governmental unit boundaries for the federal government.Governmental unit boundary information is a natural fit with the Census Bureau ’ s mission,as it has been collecting boundaries from local and tribal governments through the Boundary and Annexation Survey (BAS)since the 1940 ’ s to support census and household survey data tabulation activities.The BAS requires local and tribal government officials to certify the correctness of the boundaries for their entity as shown on maps derived from the TIGER data base,or correct the boundaries and certify the corrections.Additionally,numerous statistical area boundaries are defined throughout the decade for various programs and operations,including school district boundaries,voting district boundaries,census tract boundaries,etc.Correct boundaries and concise criteria are crucial when it comes to census and statistical data;it is in the best interests of any governmental unit to have their boundaries represented correctly when over $85 billion dollars are disbursed for federal programs nationwide over the course of a decade.

In addition to boundary information,the subcommittee also works on defining standards and metadata for other cultural and demographic themes.Currently,the subcommittee is working on the Governmental Unit Boundary Standard;it recently released the draft Address Data Content Standard for comment.Concensus among subcommittee members is more difficult to reach as time goes on;participants already have and maintain the data being defined,and every item different from what is in an existing data set requires work. Additional data will need to be collected to meet the standard,metadata will need to be documented,and data bases will need to be revised to accommodate the augmented data set.

The National Spatial Data Clearinghouse
According to Executive Order 12906,which directed the coordination of geographic data acquisition and access in the NSDI,“ clearinghouse ” means a distributed network of geospatial data producers,managers,and users linked electronically.