This document provides an introductory lecture for a course on U.S. history after 1877. The instructor, Dr. John Holmes, discusses why the course will focus on economic development and its social consequences. Specifically, it will examine the "three I's" of industrialization, immigration, and urbanization from 1877 to 1992 and how this led to social polarization and class conflict in the U.S. The lecture also summarizes key events and processes in U.S. history before 1877, including the Civil War and Reconstruction era, and sets up discussion of the Gilded Age for the next class.