Is the Apparent Decline in the Immigrant Population Real?

On August 12 my colleague Karen Zeigler and I released a widely cited report showing that the foreign-born population (legal and illegal immigrants combined) had declined by 2.2 million from January of this year to July. The analysis was based on the monthly Current Population Survey (CPS), which is collected by the Census Bureau for the Bureau of Labor Statistics (BLS). Using the same data, we also estimated that the illegal immigrant population had declined by 1.6 million over this time period.

Our report acknowledged the theoretical possibility that the observed declines might be an artifact of immigrants refusing to take part in the survey because they fear the current administration’s stepped-up enforcement efforts. Several media reports quoted others making the same critique.

However, there is as yet no evidence of this. 

Response rates to the CPS, as reported by BLS, are found in Figure 1 above. According to the BLS, a non-response occurs “when respondents are unable or unwilling to participate, interviewers are unable to locate addresses or respondents, or when other barriers exist to completing the interview.” As Figure 1 shows, there has been a long-term decline in response rates to the survey. However, the small decline in response rates between January and July of this year is very similar to the steady decline in the prior three years. 

Furthermore, as Figure 2 below demonstrates, the response rate has seen the same gradual decline even as the CPS recorded very different trends in the size of the immigration population – large measured increases in the foreign-born through January 2025, and decreases since then. 

Capturing the foreign-born population is always challenging. In a future publication, we will explore in much more detail whether the quality of the foreign-born data in the CPS has deteriorated.