This document provides an overview of Key Concept 7.1 in AP US History, which discusses the transformation of the US from a rural to urban industrial society in the late 19th and early 20th centuries. It outlines factors like new technologies, the rise of large corporations, and mass migration to cities that drove this change. It also examines the Progressive Era response to economic instability and corruption, including calls for government regulation and social reforms. Finally, it covers the New Deal programs and expanded role of the federal government during the Great Depression to provide relief, jobs, and reforms to the financial system.