text: how do we know..? i just read a question about the number of illegal aliens in the us: in responce to your question i ask ; how do you know or does your government know  the actual number of illegal aliens there are !! i've been wondering that very same thing.  it's not like they fill out a survey or even report themselves on a census.  someone in the immigration forum even went so far as to say that 96% of them are mexican!!!  i got a good laugh out of that one!  as if everyone coming up from the south is mexican!  i guess they don't realize there are other countries below mexico just as impoverished and willing to travel long ways in terrible conditions to try to find a better life.