The United States has been fortunate in never having had any extensive epidemics of plague. With the exception of a few cases, not over a dozen, that are directly chargeable to the infection of the indigenous rodents (ground squirrels), the disease has been confined to the two largest and most important cities on the Pacific Coast, San Francisco and Seattle. In each city the disease has yielded promptly to vigorous sanitary measures carried out by the public health arm of the Federal Government. Under the political organization of the Government, direct control of measures for the suppression of a disease is taken by the central sanitary authority only when a request is made by the local authorities, but it has been the experience that local authorities are prompt to make requests for assistance whenever any serious epidemic appears.