As the United states has entered its post-industrial stage of economic development, mass immigration has again become a distinguishing feature of the U.S. economy. The extant public policies that govern the size and composition of the immigrant and refugee flows, however, are largely unrelated to emerging economic considerations. Immigration is the one aspect of population and labor force growth that public policy should be able to shape and control. In all of its diverse forms, immigration presently accounts for anywhere from one-quarter to one-third of the annual growth of the U.S. labor force. By the turn of the 21st Century, it could conceivably comprise all of such growth. Immigration, therefore, is a vital determinant of the nation's economic welfare -- regardless of the reluctance of policymakers to view it as such.