It could be 1 day or 50 years. Of the 335M persons whose primary residence is in the US at this moment in time, 311M are US citizens, and 24M are noncitizens. 10M of the 24M are here illegally. Noncitizen labor force participation is about 70%, so that’s 16.8M noncitizen workers, 7M of whom are undocumented workers.
Next year on this date there might also be 16.8M noncitizen workers, but they will not be all the same people. Some died, some got deported, some left voluntarily, some became citizens, some quit working but didn’t leave the US, some newly arrived, etc. Counting the number of unique workers over a span of time, e.g. 1 year, is calculable only with documented workers.