Several government agencies and nonprofit groups gather and publish data on school shootings and other public mass killings. But because of data lags and differing definitions, getting a clear read on overall trends is surprisingly hard.
National rates of gun homicide, non-fatal gun crime and all non-fatal violent crimes have fallen since the mid-1990s. Explore the trends by age, race and gender in this interactive.
Violence plunged through the 1990s, but has declined less dramatically since 2000. Despite the drop, 56% of Americans believe gun crime is higher today than 20 years ago.