Harrington's work exposed the hidden world of poverty that existed alongside the prosperity of the American postwar boom. He argued that the American Dream was not accessible to a large segment of the population, and that systemic issues like racism, discrimination, and lack of access to education and healthcare contributed to this hidden poverty.
The book had a significant impact on public policy, contributing to the development of President Lyndon B. Johnson's "War on Poverty" programs in the 1960s.