The federal State Criminal Alien Assistance Program (SCAAP) compensates states and localities for correctional officer salary expenses for incarcerating illegal immigrants. Federal compensation is awarded via a formula for incarcerated illegal immigrants who have at least one felony or two misdemeanor convictions for violations of state or local law and who have been incarcerated for at least four consecutive days. State and local governments must apply for SCAAP reimbursement.

Data from SCAAP can help answer whether illegal immigrants are more or less likely to be criminals in the state of Texas, which has the most complete illegal immigrant criminal justice data of any state. SCAAP data include the total number of days that illegal immigrants spend in correctional institutions as well as the total amount of days that all people spend in those facilities. Combined with the estimated number of illegal immigrants in 2019, as calculated using the excellent Gunadi method, this can reveal whether the total number of days spent by illegal immigrants in Texas correctional facilities is greater than their estimated share of Texas’ population in that year. Illegal immigrant criminal arrest and conviction data in Texas are recorded by the Texas Department of Public Safety and are important for comparison.

Table 1 shows that illegal immigrants account for 3.56 percent of all days spent in Texas correctional institutions on the state and county levels. By comparison, there were about 1.87 million illegal immigrants in Texas in that year out of a total Texas population of almost 29 million – or about 6.45 percent of the total Texas population. Thus, the proportion of days that illegal immigrants spent in Texas correctional institutions in 2019 was about 45 percent below their estimated percent of Texas’s state population. In other words, the time spent by illegal immigrants in Texas correctional institutions is much less than what we’d expect just given their share of the state-wide population.

Table 1 also shows that 3.88 percent of all people convicted of a crime in Texas in 2019 were illegal immigrant individuals, which is only slightly higher than their share of time spent in correctional institutions at 3.56 percent. The illegal immigrant share of all criminal arrests was higher at 4.69 percent but that is still about 27 percent below what we’d expect given the illegal immigrant share of Texas’ total population.

One nuance to the SCAAP data is that there is a category of days spent in correctional institutions by “unknown inmates” who could be illegal immigrants. Counting all days spent by unknown inmates toward the illegal immigrant days total increase their share to 4.64 percent, which is 28 percent below their share of the state’s population. That is remarkably close to the illegal immigrant share of all arrests in Texas in 2019.

The Federation for American Immigration Reform (FAIR) incorrectly uses the SCAAP data to come to the opposite conclusion mainly because they confuse stocks with flows and make other elementary errors.

FAIR also claims that there are about 14.3 million illegal immigrants in the United States in 2019, about 3.4 million more than estimated with the Gunadi method. Funny enough, using FAIR’s higher illegal immigrant population estimate for 2019 further reduces the relative crime rate of the illegal immigrant population as estimated by SCAAP to 44 to 57 percent below their share of the population, depending on whether the “unknown inmate days” are counted as illegal immigrants.

The SCAAP data have limitations. Perhaps a large percentage of illegal immigrants spent less than 4 days in correctional institutions and so local government aren’t compensated for their time there. That would decrease their presence in the data and mean that they aren’t arrested for very serious offenses. Perhaps some local facilities don’t apply or SCAAP reimbursement. Perhaps the SCAAP criminal criteria exclude a lot of low-level illegal immigrant offenders. Regardless, it’s unlikely that SCAAP data limitations are substantial enough to hide a large number of illegal immigrant criminals in Texas’ prisons and jails. SCAAP data in Texas are just further evidence that illegal immigrants have a low crime rate compared to other residents in Texas.