Proportion of HIV reports in each city with exposure risk of male-male sexual contact (MSM), heterosexual contact (Het.) or IV drug use (IDU).

<p>(Multiple or unknown exposure categories excluded.) <b>A.</b> Principle component analysis for HIV cases 1988–1992 (top) and 1998–2002 (bottom) shows an overall national trend away from MSM and toward heterosexual and/or IDU exposures. <b>B.</b> Cities clustered based on exposure trends. MSM-biased cluster (blue) is approximately delimited by the 1990 MSM region of the PCA plot. <b>C.</b> Average socioeconomic metrics were sorted with exposure clusters. More segregated cities (measured by white/black dissimilarity index) were significantly more likely to experience a higher proportion of non-MSM HIV cases. Cities with high income inequality were more likely to report a higher proportion of IDU-associated HIV. Lowercase letters represent statistical similarity (by T-test, p<0.05).