This is fairly preliminary data, but Rick Nevin reports that if current trends keep up, we'll end 2013 with the murder rate in America at its lowest rate in over a century.
Analytically speaking, murder is an especially interesting crime
because we have pretty good homicide statistics going all the way back
to 1900. Most other crimes have only been tracked since about 1960. And
if you look at the murder rate in the chart below (the red line), you
see that it follows an odd double-hump pattern: rising in the first
third of the century, reaching a peak around 1930; then declining until
about 1960; then rising again, reaching a second peak around 1990. It's
been dropping ever since then.
This is the exact same pattern we see in lead ingestion among small
children, offset by 21 years (the black line). Lead exposure rises in
the late 1800s, during the heyday of lead paint, reaching a peak around
1910; then declines through World War II; and then begins rising again
during our postwar love affair with big cars that burned high-octane
leaded gasoline. Lead finally enters its final decline in the mid-70s
when we begin the switch to unleaded gasoline.