With the U.S. economy soaring, few cares that immigration to the United States is at its highest absolute levels. But what happens when the economy falls back to earth? High-tech immigrant workers are already competing with Americans for jobs, while unskilled immigrant laborers are becoming a permanent underclass. High immigration is creating imbalances in education, income distribution, employment, and welfare demands -- as well as tensions between immigrants and citizens and among the federal, state, and local governments. An economic slump will mean crisis. Congress and the White House need to cut back now