From 1944 through 1993, 362 cases of human plague were reported in the United States; approximately 90% of these occurred in four western states with endemic disease (Arizona, California, Colorado, and New Mexico). During each successive decade of this period, the number of states reporting cases increased from three during 1944-1953 to 13 during 1984-1993 (Figure 1), indicating the spread of human plague infection eastward to areas where cases previously had not been reported. In 1993, health departments in four states reported 10 confirmed cases of human plague to CDC; one case has been confirmed during 1994. This report summarizes information about the 11 cases of human plague reported during 1993-1994 and describes epidemiologic and epizootic trends of plague in the United States.