By Robert J. Samuelson Wednesday, May 17, 2006 President Bush's immigration speech mostly missed the true nature of the problem. We face two interconnected population issues. One is aging; the other is immigration...On the one side will be older baby boomers demanding all their federal retirement benefits. On the other will be an expanding population of younger and poorer Hispanics ... The central problem is not illegal immigration. It is undesirably high levels of poor and low-skilled immigrants, whether legal or illegal, most of whom are Hispanic... Testifying recently before Congress, University of Illinois economist Barry Chiswick -- a respected...