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Envisioning the 2020 Census
routes) as an input source. Second, it permitted limited sharing of extracts of the Master Address File (which is confidential information under Title 13 of the U.S. Code) with local and tribal governments. Specifically, this provision led to the creation of the Local Update of Census Addresses (LUCA) program, first conducted in several phases in 1998 and 1999 (see National Research Council, 2004a:62–65).
The Master Address File used to support the American Community Survey during the intercensal period is essentially an update of the 2000 census MAF, revised to include edits to the Postal Service’s Delivery Sequence File and new construction. Through these actions, the MAF, heading into the 2010 census, will be certainly more than 90 percent complete but probably not 99 percent complete. (There will almost certainly be a substantial amount of duplication as well.)
The Census Bureau will utilize two operations to increase the degree of completeness of the MAF from its status in 2008 in preparation for its use in the decennial census in 2010. First, it will again use the LUCA program, in which local governments will be asked to review preliminary versions of the MAF for completeness and to provide addresses that may have been missed (or added in error). However, even granting that LUCA will be improved over the 2000 version, it is likely that the participation will be uneven and that a substantial amount of incompleteness will remain after these addresses are added to the MAF. In anticipation of that, the Census Bureau will carry out a national block canvass, visiting each census block, and adding any missed housing units to the MAF (while collecting information from global positioning systems for all housing units).
It may be the case that for many well-established blocks in the United States a 100 percent block canvass is wasteful, given that there is little possibility in these blocks of addition or deletion of housing units over time. It would be useful to identify such blocks in advance, since then the block canvass could be restricted to the subset of blocks in need of MAF updating (this is consistent with item C.3 in Appendix A). Given the costs of a 100 percent block canvass, identifying a targeting methodology that does an excellent job of discriminating between those blocks that are very stable over time and those blocks that are likely to have recent additions or deletions (or both) would provide substantial cost savings with possibly only a negligible increase in the number of omissions (or erroneous inclusions) in the MAF. It is likely that administrative records, especially building permit records, commercial geographic information systems, and the ACS could provide useful predictors in discriminating between stable and nonstable blocks. Such targeting is already used in the Canadian census; it uses an address register that is updated intercensally, and field verification is restricted to areas where building permit data indicate the presence of significant new construction (Swain et al., 1992).