In September of 1885, a mob of about 150 white men, armed with rifles, descended upon the Chinatown in Rock Springs, Wyo. They issued an ultimatum to the people who lived there: you have an hour to leave town.
The assembled horde was angry at Chinese laborers in the region, who they blamed for keeping the choicest mining areas and depressing their wages. They felt that the Chinese were working the choicest areas of the coal mines, the part that would yield the most coal and thus the most compensation. The Chinese, they felt, were taking what was rightfully theirs.