The Justice study said that in 2011, about 70 percent of all homicides were committed with firearms, mainly handguns.
The trend in firearm-related homicides is part of a broad nationwide decline in violent crime over past two decades, including incidents not involving firearms.
Both studies concluded that most of the decline in gun homicide rates occurred in the 1990s. The Justice report found that since 1999, the number of firearm homicides increased from 10,828 to 12,791 in 2006 before declining to 11,101 in 2011.
Though researchers differ over all the reasons why gun violence has declined, many attribute it to the aging of the baby boomers. The crime rate was higher in the 1960s and 1970s when many in that large generation were teenagers, an age when higher proportions of people commit crimes.
Crime rates dropped in the early 1980s as that generation aged, rose in the latter part of that decade as the use of crack cocaine grew, then dropped again in the 1990s as the nation’s economy improved, analysts say.
The Pew report also said:
—The gun suicide rate is 6.3 per 100,000 people, and there were 19,392 suicides by firearms in 2010. That rate has declined more slowly than the firearms homicide rate, with 6 in 10 gun deaths now suicides, the highest proportion since at least 1981.
—More than 8 in 10 victims of gun homicides are men and boys.
—Fifty-five percent of gun homicide victims in 2010 were black, far beyond their 13 percent share of the population.
The Pew study chiefly used federal data from the federal Centers for Disease Control and Prevention, and the Justice Department’s National Crime Victimization Survey, a household survey conducted by the Census Bureau.