Woodrow, Karen A. 1991. “DA Evaluation Project D2: Preliminary Estimates of Undocumented Residents in 1990,” Preliminary Research and Evaluation Memorandum No. 75 (85 pp), U.S. Bureau of the Census.


Demographic analysis to evaluate census coverage requires an estimate of the undocumented population residing in the United States on April 1, 1990. There are no administrative or survey data sources on the population without documents of legal residence. The preliminary estimate for the number of undocumented residents on April 1, 1990 is 3.3 million, based on two approaches. The first approach increased the direct estimate of undocumented immigrants in the November 1989 Current Population Survey (CPS) to allow for CPS and census undercoverage. The second approach employs implicit estimates from carrying forward the alternative estimates for undocumented residents in 1980 with alternative estimates of change for periods of 1979-1986, 1979-1988, 1979-1989, 1986-1988, and 1986-1989. Allowing for CPS undercoverage, the range is 1.8 to 3.2 million with a "point" estimate of 2.5 million. Considering plausible levels for census undercoverage (20 to 30 percent) yields a range of 1.9 to 4.5 million. Without recent legalization of about 1.7 million long-term residents, the "point" estimate might have been 5.0 million, or between 4.5 and 5.5 million. The "point" estimate for undocumented residents in 1990 is 3.3 million with a likely range of 1.9 million to 4.5 million. To account for more sources of uncertainty, the true number of undocumented residents in 1990 is assumed as between 1.7 and 5.5 million. Census planning in the decade led to this empirically based estimate for the number of undocumented residents as of Census Day, 1990. In 1982, preliminary evaluation of 1980 census coverage was made without any empirical estimates for the number of undocumented residents, and those estimates were not completed until 1983-84, delaying final coverage estimates until 1985.