In the 1990s, the epidemiology of human immunodeficiency virus in the United States will more closely parallel the epidemiology of other sexually transmitted diseases. Human immunodeficiency virus prevalence rates will remain concentrated among established risk groups in currently identified epicenters of infection such as urban areas in the North and Southeast, as well as on the West coast. However, fueled largely by epidemic spread from intravenous drug users, new infections will tend to occur more frequently among minority heterosexuals in urban settings and in rural areas with proximity to drug trafficking routes. In addition, the increasingly frequent phenomenon of exchanging sex for drugs, which results in high rates of partner change, will also contribute to epidemic spread among individuals who are not identified as part of traditional risk groups.