The Chinese were the largest immigrant group in California by 1860.

Predominantly healthy male adults, the Chinese workers provide cheap labor and do not use any of the government infrastructure (schools, hospitals, etc.)

The Burlingame Treaty with China, ratified by the Senate in 1868, allows an unrestricted flow of Chinese immigrants into the country.

As time passes and more and more Chinese migrants arrive in California, violence often breaks out in cities such as Los Angeles.

As the economy soured after the Panic of 1873, Chinese immigrants were blamed for depressing workmen's wages.

Anti-Chinese riots had broken out in San Francisco during the Great Railroad Strike of 1877, and a third party, the Workingman's Party, has been formed with an emphasis on stopping Chinese immigration.

In response, Congress passes a Chinese Exclusion Act in 1879, abrogating the 1868 treaty.

President Hayes vetoes the bill, believing that the United States should not abrogate treaties without negotiation.

The veto draws praise among eastern liberals, but Hayes is bitterly denounced in the West.

Democrats in the House of Representatives attempt to impeach him  in the subsequent furor, but narrowly fail when Republicans prevent a quorum by refusing to vote.

After the veto, Assistant Secretary of State Frederick W. Seward suggests that both countries work together to reduce immigration.