[Excerpt] As the 21st Century begins, the United States is in the throes of the largest and most prolonged period of mass immigration in its history. In 2003, the foreign-born population totaled 33.5 million people (11.8 percent of the population). Moreover, the Census Bureau projects that two thirds of the nation's anticipated population growth to 392 million persons by the year 2050 will come from immigrants and their children (i.e., 82 million people). Demographic changes are converted into economic variables through labor force participation. Hence, unless there are significant policy changes, the major determinant of labor force growth in the new century will be immigration. Immigration is a policy-driven phenomenon. The current wave can be dated to the passage of the Immigration Act of 1965. The immigrant population in the United States has mushroomed in scale due to congressional indifference to the unexpected consequences of the 1965 legislation as well as the statutory refinements that followed. Immigrant population growth will continue on its expansive path unless or until public policies are enacted to change course.