Results of the study suggest that the 1,341 United States counties could be classified into 5 distinct trajectories for both their nonintimate partner homicide (non-IPH) and intimate partner homicide (IPH) rates. The results also indicate that although IPH rates had been declining over the 1980-1999 period for the majority of the 1,341 counties examined, there was evidence that rurality was significantly associated with an increased likelihood of assignment to a nondeclining IPH trajectory. Research has consistently shown that intimate partner homicide rates had been on a steady downward decline over the past two decades; however, a relatively recent movement in IPH research has emphasized the need for further dissecting the aggregate trends by factors such as gender, race, victim-offender relationship, and same-sex partners. This study sought to estimate trajectories of non-IPH and IPH rates during the years 1980-1999 while further examining the importance of rurality in affecting group membership. Figures, tables, notes, and references