According to the Center for Disease Control (CDC), the Leading Causes of Death by Age Group, for Young Black Males (for ages 15 through 34) -United States, in 2014 is homicide.
The number 1 ranked cause of death for black men by age (2014):
15-19….Homicide – 48.6%
20-24….Homicide – 47.7%
25-34….Homicide – 31.9%
Homicide drops down to third place for ages 35-44…12.9%
Homicide drops down to seventh place for ages 45-54…3.3%
Homicide is not even listed as leading cause of death for black males aged 55 and above (Cancer, Heart Disease and Stroke are the top three leading causes of death for black men after age 55.)
Based on this information it can be assumed high rates of homicide is connected to early manhood among black men and boys. By their mid-thirties homicide rates drop precipitously.
Homicide is not the Leading Cause of Death of White Men at any age.