Does the U.S. have a gun problem or a mental illness problem?

The folks at ProPublica have put together an impressive package of charts, graphs and links that cover numerous aspects of the nation’s gun debate by offering facts and statistics for each state. They also offer some fantastic interactive graphics from news outlets across the nation.

The categories are diverse: gun sales, gun laws, gun distribution, mass shootings, firearms deaths, NRA political influence, the stance of each member of Congress on gun issues, and much more.

While the NRA warns of constant Democratic attempts to impose new gun controls, one set of maps and charts shows just how successful the NRA has become at the state level -- rolling back 99 gun laws in just four years.

Overall, the flow of guns and the interaction between states becomes fairly obvious when you scan these images. In Michigan, for example, more than one-third of gun purchases are made outside of the state.

One link sends you to an interactive graphic with details for all mass shootings in the U.S. from 1982-2012. The unmistakable “take away” from this map is that most of these slaughters were perpetrated by men who showed signs of mental instability or illness prior to the incident, and most of the shooters bought their guns legally.

Gun advocates would be wise to latch onto that information and make the case that blocking access to firearms for those who show signs of mental problems is the nation's real "gun problem."