Illustration of the Rock Springs Massacre from Harper’s Weekly

H. W. Brands, writing in The American Colossus: The Triumph of Capitalism 1865-1900 (p. 300):

The formal effect of the Chinese Exclusion Act was to bar most new immigration from China, but its informal effect was to declare open season on Chinese already in America. Within months of the act’s passage, what the Chinese called the “driving out” began. White hooligans waged racial war against Chinese across much of the West, killing twenty-eight in Rock Springs, Wyoming, thirty-one on the Snake River in eastern Washington, and smaller numbers elsewhere. Occasionally whites stuck up for their Chinese neighbors, if sometimes from selfish motives. A white gambler in Denver pulled six-guns on an anti-Chinese mob and told them to desist. “If you kill Wong, who in the hell will do my laundry?” he demanded. But in most places the mobs had their way. Rural communities of Chinese largely disappeared, their inhabitants driven off, their homes burned, their property seized by those doing the driving.