The United States can really be divided up into three types of places. Places where there are no murders, places where there are a few murders, and places where murders are very common.
In 2014, the most recent year that a county level breakdown is available, 54% of counties (with 11% of the population) have no murders. 69% of counties have no more than one murder, and about 20% of the population. These counties account for only 4% of all murders in the country.