You can go through a whole recitation of a long list - far too long a list - of mass murders by gun, in America over the last 30 years. It seems like there's a shooting damn near every day?

In the last week, other than the terror act in Denver, there were 17 people shot in an Alabama bar, and a New York cop shot his own son accidentally in a darkened hotel room. That's right - a trained cop shot his own son. So for those of you who think like crazy Texas Congressman Louis Gohmert, that a moviegoer with a concealed weapon could have stopped the shooter? Think again.

The larger point is this: These shootings have happened all over the country - and probably closer to you than you think.

Thanks to the hard work of the team at Mother Jones magazine, here's a map showing where some of the most horrific mass murders caused by guns have happened in the U.S., over the last 30 years.