“…States with higher STD rates have a larger number of persons who engage in risky behaviors associated with STD transmission (Bernstein et al, 2004;Jennings, Curriero, Celentano, & Ellen, 2005). From an infectious disease perspective and from a clustering perspective, STD rates in a given state are associated with similar STD rates in neighboring states and hence are not randomly distributed in space (Aral, Fullilove, Coutinho, & Van Den Hoek, 1992;Bernstein et al, 2004;Elliott et al, 2002;Fox et al, 1998;Jennings et al, 2005;Kerani, Handcock, Handsfield, & Holmes, 2005;Koumans et al, 2000;Webster, Rolfs, Nakashima, & Greenspan, 1991;Wylie, Cabral, & Jolly, 2005). Regional variation in rates of gonorrhea and syphilis, for example, continue to exist even when these rates are examined separately for Whites and for African-Americans (Farley, 2006).…”