[Excerpt] Of the multiple explanations for the post-World War II immigration experiences of those advanced industrial nations where the phenomena occurred, the most pernicious has been that immigrants are needed to do the "dirty work." Despite the fact that efforts to characterize the general employment patterns of immigrants in different industrial societies "has proved frustrating," Michael Piore observed in 1979 that "the only immigrant jobs that seem common throughout the industrial world are menial jobs". Likewise, much of the debate in the United States that preceded the enactment of the Immigration Reform and Control Act of, 1986 (IRCA) centered on the efficacy of the assertion that the United States economy actually needed illegal immigrants to fill certain menial jobs that would not otherwise be filled. The general thesis of efforts made to explain these tendencies has been that the structure of labor markets changes over time. As advanced industrial societies have evolved over the past two centuries from being agriculturally based societies, their occupational opportunities have become considerably more diverse. Nonetheless, some labor economists have argued that, by the late twentieth century, many of these societies have sustained perceptible patterns of job clustering. They have witnessed the creation of a dual labor market. Under this analysis, these economies generate both primary sector jobs (i.e., jobs characterized as having high wages, good fringe benefits, job security, and promotion opportunities) and secondary sector jobs (i.e., jobs characterized as having low wages, few fringe benefits, little security, and are of a dead-end nature). The relevant question, therefore, has been how do these advanced societies find workers to fill these secondary sector jobs?