microscopic studies of the workers in particular industries in particular cities. The consensus has been that the workers had their own political and cultural value system. The political values were based on a producer's ethic, that is the working class was the truly productive sector of society, and expressed a version of republicanism that was similar to the middle class version. This enabled the businessman's party, the Republican party, to enjoy a strong base among Protestant blue collar workers, and prevented the emergence of a strong Socialist movement. 20th century The Progressive Era, with its emphasis on factualism and scientific inquiry produced hundreds of community studies, mostly using descriptive statistics to cover issues of poverty, crime, migration, religiosity, education, and public health. The emergence of systematic social science, especially sociology, shifted the center of class studies into sociology departments. The most representative example was the Middletown books by Robert Lynd and Helen Lynd, which gave a microscopic look at class structures in a typical small city (Muncie, Indiana). After 1960 localized studies gave way to national surveys, with special emphasis on the process of social mobility and stratification. A classic theme was trying to see if the middle class was shrinking, or if the opportunities for upward mobility had worsened over time. After 1960 a growing concern with education led to many studies dealing with racial integration, and performance in schools by racial and gender groupings. The disposable income of the American upper class was sharply reduced by high income tax rates during the 1930s, 40s, and 50s. During this period corporate executives had relatively modest incomes, lived modestly, and had few servants. See also American Dream California Dream American middle class American upper class Social history References Further reading Beckert, Sven, and Julia B. Rosenbaum, eds. The American Bourgeoisie: Distinction and Identity in the Nineteenth Century (Palgrave Macmillan; 2011) 284 pages; Scholarly studies on the habits, manners, networks, institutions, and public roles of the American middle class with a focus on cities in the North. Beeghley, L. The Structure of Social Stratification in the United States (Pearson, Allyn & Bacon; 2004). Bolton, Charles C. "Planters, Plain Folk, and Poor Whites in the Old South." in Lacy K. Ford, ed., A Companion to the Civil War and Reconstruction, (2005) 75–93. Flynt, J. Wayne, Dixie's Forgotten People: The South's Poor Whites (1979). deals with 20th century. Gilbert, D. The American Class