Once you acknowledge the plain fact that the U.S. has deliberately engineered -- and maintained for over a century -- an agricultural system dependent on migrant labor, you see that "the undocumented" aren't an illicit foreign presence, but a hyper-exploited domestic caste.

https://www.nytimes.com/2020/04/02/us/coronavirus-undocumented-immigrant-farmworkers-agriculture.html

. @DanielDenvir's book offers an excellent overview of how shifts in U.S. immigration law over the 20th century recoded this part of the labor-force as "illegal," and how nativists exploited this designation in popularizing the idea of an immigration crisis https://www.versobooks.com/books/2858-all-american-nativism