The enterprise of making small-area population estimates rests on a foundation composed of both methodology and data.  While the particular data used in an estimates model varies considerably across the spectrum of local and regional planning agencies, state demographic agencies, federal agencies, and private data purveyors, the fundamental methodologies are comparatively rather few in number.  The activities of state and local agencies preparing population and housing estimates has been documented in the Current Population Reports series (U.S. Bureau of the Census, 1990).  The most recent of these reports categorized the methods used as follows: Component, Regression/Ratio, Correlation, Housing Unit, Vital Rates/Censal Ratio, Cohort Component, Composite, Survey, Proration, and Other. Each of the specific methods is well documented, including two books devoted to explicating the procedures (Lee and Goldsmith, 1982; Rives, et al., 1995).  Hence, a fairly broad array of methods exists for preparing estimates.