The Bureau of Justice Statistics just put out a report on violent crime among households with children. The trend over the last two decades looks awfully good:
That chart, to borrow the sociologist Chris Uggen's description, "shows the percentage of households with children in which at least one member age 12 or older experienced nonfatal violent victimization (rape, sexual assault, robbery, aggravated assault, and simple assault) in the previous year." The period covered goes from 1993 to 2010, and as you can see, the total has been declining sharply and steadily. (The sudden spike in 2006 represents a change in methodology.) "These numbers still seem high to me," Uggen adds, "but I think it is because simple assault (which encompasses a pretty broad range of behavior) accounts for the bulk of the violence."