Third World immigrants bring the Third World with them. Particularly given the massive numbers over such short time frames, it's an inescapable reality. Already many cities and even regions have begun to resemble the slums of Tijuana.
The nature of immigration has also changed. Many of the early generations of immigrants to this country (or the colonies) came for freedom and opportunity. If they wanted economic security they would have likely been better off to stay where they were, because the job of carving a civilization out of hostile wilderness was not an easy one. But they wanted something deeper than that, and that is what makes the foundation of a nation. Recent immigrants and border-jumpers, while there are still some motivated by the pursuit of freedom, are more likely to be motivated by a desire to enjoy the spoils and largesse of a successful civilization that has entered (terminal?) decline and decadence. In other words, their motivation for immigration is little different from the cockroaches and ants that "immigrate" into your kitchen if you leave food laying out for them.
All of this is guaranteeing the destruction of the USA. This country will become just another part of the Third World, and that is exactly the desire of people like Obama.