just to chime in a little..I was involved ina rather lengthly thread on the subject of immigration on a history dsicussion board..one of the salient points made was that supplying water and power to an increasing influx of immigrants was really becoming a problem..we are approaching 300 million and this country just doesn't have the infrasturcture to handle many more...doesn't southern cali have regular water shortages and rolling blackouts..maybe soemone with some more knowledge couild contribute..but to me,it isn't neccassarily a question of can/do they contribute their fair share,but can we simply keep adding to our populace?...circa 300 million means we can't compare the situations in the 1800s and 1900s with now