“How many unauthorized immigrants are there in Virginia?” This is a question we get asked quite often, but there is really no good data or any official statistic on it. Migration numbers are difficult to estimate and counting the number of unauthorized or undocumented migrants can be especially challenging given the limited availability of records. Neither censuses nor surveys conducted by federal agencies directly ask the question of immigration status; they cover only citizenship. In the American Community Survey (ACS), which is the largest nationwide survey replacing the decennial census long form, individuals are asked about their citizenship status in the following three categories: native-born/U.S.-born citizen, naturalized U.S. citizen, or non-U.S. citizen. Non-citizens include both authorized and unauthorized immigrants, and there is no information about a non-citizen’s immigration status. In addition, since surveys require self-reporting, unauthorized immigrants tend not to answer the citizenship question or avoid filling out the survey altogether; therefore, some are missing even from the count of non-citizens.