By conventional wisdom, El Paso, Texas should be one of the scariest cities in America. In 2007, the city's poverty rate was a shade over 27 percent, more than twice the national average. Median household income was $35,600, well below the national average of $48,000. El Paso is three-quarters Hispanic, and more than a quarter of its residents are foreign-born. Given that it's nearly impossible for low-skilled immigrants to work in the United States legitimately, it's safe to say that a significant percentage of El Paso's foreign-born population is living here illegally.

El Paso also has some of the laxer gun control policies of any non-Texan big city in the country, mostly due to gun-friendly state law. And famously, El Paso sits just over the Rio Grande from one of the most violent cities in the western hemisphere, Ciudad Juarez, Mexico, home to a staggering 2,500 homicides in the last 18 months alone. A city of illegal immigrants with easy access to guns, just across the river from a metropolis ripped apart by brutal drug war violence. Should be a bloodbath, right?

Here's the surprise: There were just 18 murders in El Paso last year, in a city of 736,000 people. To compare, Baltimore, with 637,000 residents, had 234 killings. In fact, since the beginning of 2008, there were nearly as many El Pasoans murdered while visiting Juarez (20) than there were murdered in their home town (23).

El Paso is among the safest big cities in America. For the better part of the last decade, only Honolulu has had a lower violent crime rate (El Paso slipped to third last year, behind New York). Men's Health magazine recently ranked El Paso the second "happiest" city in America, right after Laredo, Texas—another border town, where the Hispanic population is approaching 95 percent.

So how has this city of poor immigrants become such an anomaly? Actually, it may not be an anomaly at all. Many criminologists say El Paso isn't safe despite its high proportion of immigrants, it's safe because of them.

"If you want to find a safe city, first determine the size of the immigrant population," says Jack Levin, a criminologist at Northeastern University in Massachusetts. "If the immigrant community represents a large proportion of the population, you're likely in one of the country's safer cities. San Diego, Laredo, El Paso—these cities are teeming with immigrants, and they're some of the safest places in the country."

If you regularly listen to talk radio, or get your crime news from anti-immigration pundits, all of this may come as a surprise. But it's not to many of those who study crime for a living. As the national immigration debate heated up in 2007, dozens of academics who specialize in the issue sent a letter (pdf) to then President George W. Bush and congressional leaders with the following point:

One of the signatories was Rubén G. Rumbaut, a sociologist who studies immigration at the University of California, Irvine. Rumbaut recently presented a paper on immigration and crime to a Washington, D.C. conference sponsored by the Police Foundation. Rumbaut writes via email, "The evidence points overwhelmingly to the same conclusion: Rates of crime and conviction for undocumented immigrants are far below those for the native born, and that is especially the case for violent crimes, including murder."

Opponents of illegal immigration usually do little more than cite andecdotes attempting to link illegal immigration to violent crime. When they do try to use statistics, they come up short. Rep. Steve King (R-Iowa), for example, has perpetuated the popular myth that illegal immigrants murder 12 Americans per day, and kill another 13 by driving drunk. King says his figures come from a Government Accountability Office study he requested, which found that about 27 percent of inmates in the federal prison system are non-citizens. Colorado Media Matters looked into King's claim, and found his methodology lacking. King appears to have conjured his talking point by simply multiplying the annual number of murders and DWI fatalities in America by 27 percent. Of course, the GAO report only looked at federal prisons, not the state prisons and local jails where most convicted murderers and DWI offenders are kept. The Bureau of Justice Statistics puts the number of non-citizens (including legal immigrants) in state, local, and federal prisons and jails at about 6.4 percent (pdf). Of course, even that doesn't mean that non-citizens account for 6.4 percent of murders and DWI fatalities, only 6.4 percent of the overall inmate population.