The number of crimes committed with firearms has dropped significantly since the early 1990s. That's the good news. The bad news is that firearms are still a common component of crime, and that gun shows are still a source of the guns criminals use in crime. The data offers both advocates and opponents of expanded gun measures fodder for their arguments, and rationalization for their votes.

Two days ago, it seemed as though Senator Jeff Flake of Arizona was receptive to an expansion of background checks to cover sales at gun shows and online, key components of the compromise proposal from Senators Joe Manchin and Pat Toomey that he voted to filibuster last month. But that was a different day than yesterday. Yesterday, the Washington Post reports, he was much more forceful.

“I’m not reconsidering my position, I think they ought to go back to the drawing board,” Sen. Jeff Flake (R-Ariz.) said. “I want to strengthen our background check system, but whether they can do that with the Toomey-Manchin proposal, I don’t know.”

Nor did New Hampshire's Kelly Ayotte — another senator closely watched for a potential reversal on the measure — seem chastened by the political damage she took after the vote. In an opinion piece posted at the news site Patch, she defended her support of background checks:

Despite what the false attack ads say, I helped introduce and voted for the Protecting Communities and Preserving the Second Amendment Act, which improves the existing background check system, addresses mental health gaps in the criminal justice system, boosts resources to improve school safety, and criminalizes gun trafficking and straw purchases. The legislation also puts teeth into the law by creating a high level federal task force to increase the prosecution of gun-related violence.

The bill to which Ayotte refers was centered around an NRA-approved emphasis on increasing consideration of mental health in background checks.

Into this crowded political moment stepped new data on gun violence from the Department of Justice. A lengthy report from its Bureau of Justice Statistics crunched data on gun violence and crime since 1993.

The key finding is that there's been a massive drop. Since the early 1990s, in parallel with overall crime rates, the number of incidents of gun violence decreased steadily and then remained fairly flat.

Interestingly, Pew Research found that people are largely unaware of this drop. Forty-five percent of Americans thought gun crimes had increased since the 1990s; 10 percent thought they'd gone down.

That may in part be due to the fact that the use of firearms in crimes have remained fairly steady. In other words — crime overall has declined, but guns are still as commonly used in crime as they used to be.

More relevant to the current discussion is how the firearms used in crimes were obtained. Parsing the data from the Department of Justice, it's clear that overall trends have remained consistent. Between 1997 and 2004 — the two years for which data is provided — the firearms felons used in crimes were most likely acquired from family or friends or acquired illegally.

Looking at each year individually, the DOJ breaks down those categories.

Criminals in both years were about equally likely to buy a firearm in a retail store as on the black market.

Interestingly, the rates at which criminals bought weapons from various sources dipped between 1997 and 2004, with one exception: gun shows. Criminals bought a smaller percentage of weapons from retail stores, pawn shops, and flea markets between the two years, but at a consistent rate from gun shows. Albeit, only a fraction of a percent of all of the guns purchased.

There's one more set of data that's useful for the current political debate. As we and our colleagues at Atlantic Cities have noted, attitudes toward gun crime differ widely between urban and rural residents. In large part, that's because gun crime is far more prevalent in the former.

Most of those opposing the gun compromise last month were from rural states. Ayotte and Flake represent states that are more in the middle — a fact that is reflected in their positions on the issue.

Photo: Weapons collected during an NYPD narcotics raid. (AP)