This morning, I was skimming the actual study the news is based on. The authors conclude:
Quote:
Although by and large the increased injury–related mortality risk to rural residents is driven by these motor vehicle crash–related injury deaths, other less common injury mechanisms with increased risk of death in rural areas include machinery injuries, injuries from being struck, and environmental/exposure injuries

So, it's mostly car crashes that drive this urban/rural difference. They found that homicide risks were indeed higher in urban areas, but the motor vehicle risk for rural folks was much bigger and overshadowed the homicide risk.