Guns and the Drop in the Violent Crime Rate

President Obama undoubtedly didn’t intend it, but he deserves some credit for the recent report that all violent crime rates dropped in 2009, murder rates by 7.4 percent, robbery rates by 9 percent: His election caused gun sales to skyrocket, and crime rates to plummet.

Gun sales started notably rising in October 2008, and sale really took off immediately after Obama won the presidential race: 450,000 more people bought guns in November 2008 than bought them in November 2007. That’s over a 40 percent increase in sales. By comparison, the change from November 2006 to November 2007 was only about 35,000. Over the last decade, the average year-to-year increase in monthly sales was only 21,000.

The higher sales continued well beyond November 2008: about 3.15 million more people bought guns in the 14 months after the election than in the preceding 14 months. The National Instant Criminal Background Check System, or NICS, doesn’t tell us how many guns each person bought, just the number of people who bought them. Most likely, though, gun sales rose by more than the number of people who purchased them.

At the same time gun sales were soaring, there was an unusually large drop in murder rates. The 7.4 percent drop in the murder rate was the largest drop in murder rates since the 1999. For those who don’t remember, 1999 — when Bill Clinton was president and Columbine occurred — was another time when gun sales soared. With Clinton domestic-policy advisers such as Elena Kagan pushing hard for more gun control, Americans were worried that more gun bans were coming; in response, gun sales soared.

Higher arrest and conviction rates, longer prison sentences, and the more frequent use of the death penalty all reduce crime, and so does letting victims defend themselves with guns. More certain or greater penalties make it more risky for criminals to commit crime. Victims who can defend themselves can also make committing crime more dangerous and deter criminals.

Americans living in the District of Columbia and Chicago have seen this phenomenon firsthand. After bans went into effect in both cities, murder rates rose dramatically. The District’s murder rates then plunged by 23 percent in 2009 after the Supreme Court threw out D.C.’s gunlock laws and handgun ban. After that 2008 decision, 70,000 D.C. residents were able to use their long guns for self-defense. As my research in the just-released third edition of More Guns, Less Crime shows, murder rates don’t fall and tend to climb when guns are banned.

If President Obama really understood that it reduces crime to let law-abiding citizens defend themselves, it is unlikely that gun sales would have had to increase. If the Supreme Court strikes down the Chicago gun ban this month, Americans may get to see yet again that more guns means less crime.

John R. Lott Jr. is a FOXNews.com contributor. He is an economist and the author of "More Guns, Less Crime (University of Chicago Press, 2010), the third edition of which was published in May.".