Ok, someone could take the pew research numbers on illegal immigration by metropolitan region, and then correlate that to Spanish radio listenership in those metros based on the Nielsen tlr data. As much fun as that is, and as much as I appreciate the HN readers demand such validation, I’ll let someone else run those numbers.
https://www.pewresearch.org/fact-tank/2019/03/11/us-metro-ar...
CBP also maintains statistics: https://www.cbp.gov/newsroom/stats/sw-border-migration
In the private sector, Pew Research (a well regarded, nonpartisan institution) generates statistics using loads of studies. See, e.g., https://www.pewresearch.org/fact-tank/2019/06/12/us-unauthor...
These are all readily found using some basic Google searches.