Like many others you have a misunderstanding of legal status versus economic metrics. Illegals can and do work in the U.S., despite lacking legal authorization. They often take jobs in sectors like agriculture, construction, or hospitality, typically under the table or using borrowed or fake credentials. So, they are very much part of the workforce, even if not legally recognized as such.
The unemployment rate is calculated based on the Current Population Survey. The CPS counts people as employed if they did paid work during the survey week, regardless of legal status. It counts them as unemployed if they’re jobless, actively looking for work, and available to take a job—again, regardless of legal status. The catch? The CPS doesn’t explicitly ask about immigration status, so undocumented workers are included in these numbers implicitly, not separately tracked.
Their employment DOES reduce the unemployment rate, indirectly. The unemployment rate is the number of unemployed people divided by the labor force (employed + unemployed). If undocumented immigrants are working (counted as employed), they increase the denominator’s "employed" portion without adding to the "unemployed" numerator. This lowers the percentage, assuming the number of unemployed stays constant. For example, if 100 people are in the labor force, 5 are unemployed (5% rate), and 10 undocumented workers get jobs, the labor force becomes 110, with 5 still unemployed—dropping the rate to 4.5%.
PS. I hope this helps. If you are in possession of any facts that would ten to refute this, please feel free to submit for further discussion.