The "deindustrialization" thesis of Bluestone and Harrison asserts that the replacement of domestic with foreign manufacturing begun by United States corporations in the late 1960s resulted in a "hollowing out" of American industry, whereby workers displaced from manufacturing jobs through massive plant closings found themselves moving more or less permanently into lower-paying, less secure jobs or into unemployment. Critics of the deindustrialization thesis have argued that new service and high-technology sectors of the United States economy have recently created a substantial number of jobs. While these critics do not deny the painful aspects of this transition from an industrial to a service- and information-based economy, they argue that it will be short-term, and a necessary evil if the United States is to have long-term increases in living standards. Critics of the emerging economy, however, point to disturbing evidence of an "hourglass" effect: a shrinking middle tier of managerial and blue-collar unionized workers and consequent polarization of incomes. The emergence of a technical and financial elite, they argue, has brought forth a host of low-wage jobs to service the new economy, and it is this service sector that many ex-industrial workers must seek.