Social class is an important theme for historians of the United States for decades. The subject touches on many other elements of American history such as that of changing U.S. education, with greater education attainment leading to expanding household incomes for many social groups. The overall level of prosperity grew greatly in the U.S. through the 20th century as well as the 21st century, anchored in changes such as growing American advances in science and technology with American inventions such as the phonograph, the portable electric vacuum cleaner, and so on. Yet much of the debate has focused lately on whether social mobility has fallen in recent decades as income inequality has risen, what scholars such as Katherine S. Newman have called the "American nightmare."[1]
For most of American history, social class barriers were fundamentally rigid, with various private and public institutions enforcing rules based on racial segregation and other forms of classifying people based on prejudices such as antisemitism and Hispanophobia. All this changed greatly with the rise of broad-based prosperity in the aftermath of World War II and efforts to expand Constitutional civil rights under the law to groups such as African-Americans and Hispanic-Americans. Issues regarding social class have remained hot-button topics in U.S. politics, with the American Great Recession causing massive socio-economic harm across the country from southerners to northerners to working-class whites to middle-class blacks