U.S. Sen. Tom Coburn, who used sleight of legislative hand to see that national park visitors could arm themselves, boasted the other day that violent crime in the parks has decreased 85 percent thanks to that legislation. Unfortunately, he was far from accurate with that statement, according to fact checkers.

It was the Oklahoma Republican who, back in 2009, attached an amendment to credit card legislation to allow national park visitors to carry firearms with them as long as they were allowed to carry them in the state in which the park in question was located. That legislation, amid much controversy, took effect the following year.

Last week, while appearing on the MSNBC show Morning Joe, Sen. Coburn boasted that "(I)n 2010, everybody said you can't dare let guns go into the national parks, and of course the rapes, murders, robberies and assaults are down about 85 percent since we did that."

But a check of the facts by Politifact, a "project of the Tampa Bay Times and its partners to help you find the truth in politics," discovered that the senator not only misstated the facts, but did so by an incredibly wide margin.

Of course, crime in national parks is generally far lower than in other areas of the country, particularly major metropolitan areas. As a result, even a few swings -- up or down -- in crime can result in significant percentage changes.

Nevertheless, Sen. Coburn's statement was far off the mark, Politifact found. When the fact checkers contacted the senator's staff, they acknowledged that "(T)he numbers show crime rates have declined, but he misspoke when he mentioned 85 percent. On balance, the facts support our conclusion that crime rates would go down under our policy, not the conclusion of the amendment’s critics who said that allowing guns in national parks would lead to more crime."

But Politifact didn't take that statement on face value, instead digging into the FBI crime numbers and analyzing them. What they found was that the senator's staff was selective in the crime numbers it used to justify Sen. Coburn's comments. For example, while the gun law took effect in 2010, the senator's staff used 2008, not 2009, as the base year. But even if one used 2008 as a base year, murders in the parks actually increased from then until 2011, the most recent year that crime statistics are available for, from five to seven.

And if you use 2009 as the base year, which Politifact says would be a more accurate approach, murders jumped from three to seven in 2011 -- and there were 15 in 2010, the year the legislation took effect.

Statistically, murders in the parks rose 133 percent from 2009 to 2011, notes Politifact, and aggravated assaults went up 9 percent. The number of forcible rapes in 2009 and 2011 were 34 for each year, while robberies decreased 9 percent, from 64 to 58.

Lump all violent crimes together, and they increased 5 percent from 2009, the year before the gun legislation took effect, to 2011, the year after it took effect, Politifact found. The bottom line, according to the fact checkers, was Sen. Coburn's claim was far off-base. And more thorough analysis is needed before one can claim what impact allowing guns to be carried in national parks has, noted Politifact.

Finally, we’ll point out that Coburn’s stated decline may -- or may not -- have been caused by the deterrence of having guns around. But if they were a cause for the decline from 2008 to 2011, what’s to stop someone from arguing that they were the cause of the increase from 2009 to 2011? The numbers alone simply don’t tell us.