"Progress and Poverty" is George's first book, which sold several million copies, exceeding all other books sold in the United States except the Bible during the 1890s. It helped spark the Progressive Era and a worldwide social reform movement around an ideology now known as 'Georgism'. Jacob Riis, for example, explicitly marks the beginning of the Progressive Era awakening as 1879 because of the date of this publication. The Princeton historian Eric F. Goldman wrote this about the influence of "Progress and Poverty": For some years prior to 1952 I was working on a history of American reform and over and over again my research ran into this fact: an enormous number of men and women, strikingly different people, men and women who were to lead 20th century America in a dozen fields of humane activity, wrote or told someone that their whole thinking had been redirected by reading "Progress and Poverty" in their formative years. In this respect no other book came anywhere near comparable influence.