Neighborhood Change Database 2010
The data in CensusCD Neighborhood Change Database are constructed from an extensive subset of the Census variables for each decade (about 1,000 variables for each year).
The data in the Neighborhood Change Database is:
- 1970 variables 🗗
- 1980 variables 🗗
- 1990 variables 🗗
- 2000 variables 🗗
- 2010 Summary File 1 variables 🗗
- 2006-10 American Community Survey (ACS) variables 🗗
For a more complete description of the variables, geographies and methodologies please refer to the Data Users' Guide. The individual sections are pdfs, their size is indicated in parentheses:
- 2010 NCDB Data Users Guide (PDF - 11 MB)
- Overview and History (PDF - 225 KB)
- Appendix A: State Codes (PDF - 39 KB)
- Appendix B: County Codes (PDF - 335 KB)
- Appendix C: Metropolitan Area Codes (PDF - 259 KB)
- Appendix D: Aggregation Error for New England Metro Areas and for Places (PDF - 59 KB)
- Appendix E: Data Dictionary (PDF - 894 KB)
- Appendix F: Census Source Tabulation Matrices - 1970 (PDF - 27 KB)
- Appendix G: Census Source Tabulation Matrices - 1980 (PDF - 95 KB)
- Appendix H: Census Source Tabulation Matrices - 1990 (PDF - 256 KB)
- Appendix I: Census Source Tabulation Matrices - 2000 (PDF - 445 KB)
- Appendix J: Description of Tract Remapping Methodology (PDF - 38 KB)
The Neighborhood Change Database is based on the geographic unit of the Census Tract. The Census Tract is the Census Bureau's statistical equivalent of a large neighborhood (with an average of about 4,000 people).
You can select any of the 6 geographical levels:
- Nation (United States)
- States (50 + District of Columbia)
- Counties (3,141)
- Tracts (depends upon the census 35-73,057)
- CBSA – Core Based Statistical Areas
- CSA – Combined Statistical Areas
The data will be presented at the tract level only, but each record has additional geographic identifiers for larger geographies (such as county, metropolitan areas, places) so it is possible for you to summarize the tracts in other database or statistical programs.The geographic identifiers that are included in NCDB for 2010 tract boundaries are: State, Region, Division, County, County Subdivision, Place, American Indian Area/Alaska Native Area/Hawaiian Home Lands, American Indian Tribal Subdivision, Alaska Native Regional Corporation, Metropolitan Statistical Area/Micropolitan Statistical Area, Metropolitan Division, Combined Statistical Area, New England City and Town Area, Combined New England City and Town Area, Congressional District, State Legislative District (Upper Chamber), State Legislative District (Lower Chamber, Voting District, Zip Code Tabulation Area, School District (Elementary), School District,(Secondary), School District (Unified).
The 1970 and 1980 censuses did not have full tract coverage of the US. The tracts are predominantly located in urban areas. By 1990 the US was fully tracted and all parts of the country were covered.
The actual remapping procedure for converting data from 1970, 1980, 1990, 2000 tracts to 2010 tract boundaries is quite complicated. Those wishing more a technical explanation of this task should consult Appendix J of the Data Users' Guide (PDF). The basic procedure was to use geographic information system (GIS) software to overlay the boundaries of 2000 tracts with those of an earlier year. This allowed us to identify how tract boundaries had changed between censuses. We then used 2000 block data to determine the proportion of persons in each earlier tract that went into making up the new 2010 tract. For example, if a 2000 tract split into two tracts for 2010, the population may not have been divided evenly. Our method allows us to determine the exact weight to allocate to each portion.
These population weights were then applied to the various 1970, 1980, 1990, and 2000 tract level NCDB variables to convert them to 2010 tract boundaries. The population weights were used to convert all variables based on counts of persons, households, and housing units, all counts based on subpopulations (such as black persons or elderly households), and all aggregate data (such as aggregate household income). Proportions (such as the proportion of Hispanic persons) were remapped by first converting the respective numerator and denominator values (Hispanic persons and total persons, respectively) and then recalculating the proportion.
Understanding how neighborhoods change over time is fundamental to addressing the problems and opportunities of America's communities. Many people are not aware, however, that data obtainable from the U.S. Bureau of the Census cannot be used directly for these purposes, because of many changes in census tract boundaries and variable definitions between census years. In the early 1990s, with funding from the Rockefeller Foundation, the Urban Institute made adjustments as necessary to create the first national data file with consistently defined tract level census data for 1970, 1980 and 1990. That file has since been used as the basis for important research on how the nation's communities changed over those decades.
Rockefeller has again provided funding to allow the Urban Institute to add 2010 census data to the file. To do so, the Institute has collaborated with GeoLytics again. In 2005 GeoLytics added the 2000 data and also transformed the product to make it much more user friendly and technically superior to the earlier version in a number of respects. GeoLytics applied their proprietary weighting tables for 1970, 1980, and 1990 to carefully convert past census data to new 2000 tract boundaries. This procedure allows NCDB data to be accurately compared over time for the exact same geographical boundaries.
Another improvement is that the NCDB data products are being released on CD-ROM using GeoLytics' proprietary data compression and mapping technology. The data can be accessed using the menu-driven mapping and analysis software or the data can be extracted for use in external database, mapping, and analysis packages. The collaboration has drawn on the strengths of both organizations, and resulted in a product that is a significant tool for policy-makers, researchers and community practitioners interested in neighborhood change.