1. Estimating the Unauthorized Immigrant Population and its Geographic Distribution within Texas Counties Miguel Flores, Lila Valencia, & Lloyd Potter University of Texas at San Antonio Applied Demography Conference January 2012

2. Background • Conventionally, estimation of the unauthorized population is produced using the residual method (Warren 2011; Passel 2010, 2011) • Estimates of legal foreign born residents are subtracted from estimates of foreign born (either from the Current Population Survey (CPS) or the American Community Survey (ACS)) • Most commonly used national and state estimates include Pew Hispanic Center, Dept. of Homeland Security, and Warren estimates

3. Background

4. Background Source: Pew Hispanic Center, 2011

5. Background Source: Warren, 2010

6. Background • Residual method produces some challenges when attempting to produce estimates at lower geographies • Hill & Johnson (2011) employ a methodology that combines census population data with newadministrative data that allows for estimation of the total unauthorized population and its distribution at sub-state level geographies

7. Literature Review • 80 percent of unauthorized immigrants report filing federal income taxes and about 75 percent of unauthorized report having payroll taxes withheld (Porter 2005; Hill et al. 2010). • Since immigrants without work authorization do not have valid social security numbers, many instead use Internal Revenue Service (IRS) issued Individual Taxpayer Identification Numbers (ITIN) when filing tax returns. • Hill et al. (2011) have shown a high correlation between the ITIN filers and unauthorized immigrant estimates in the U.S.

8. Methodology • ITINs data are available for tax years 2000 to 2008 at the zip code level. • Not all unauthorized immigrants file tax returns and not all ITIN filers are unauthorized (Hill et al. 2011). • To address this issue, we incorporate sociodemographic characteristics related to the unauthorized immigrant status from the ACS.

9. Methodology • The population is restricted to foreign-born residents (ITIN/Warren Estimate)ts = Xtsα + Wtsβ + Ztsγ + εts • Final Model:

10. Methodology • The unauthorized estimates were totaled and scaled to match Warren’s estimate of unauthorized for the state. • These estimates are then used to generate counts of the unauthorized population at the sub-state level. • Estimates of the unauthorized population are produced for county and zip code for the state of Texas. • The analysis is replicated for several years, 2000, 2005 and 2008.

25. Percentage of Total Population

28. Results • Preliminary county and zip code level estimates appear to be in line with: • Agricultural areas • Urban areas • Areas of high employment • Areas experiencing Hispanic population growth • Areas with substantial foreign born population • These areas include counties and zip codes in the Dallas-Fort Worth-Arlington, Houston-Baytown-Sugarland, and Austin-Round Rock metropolitan areas, large border counties, and counties in parts of East Texas.

29. Future Directions • Estimate model specific to Texas • Explore trends from available data