We know that the US-Mexico border where the President just sent 1,200 National Guard troops has actually experienced a drop in crime over the last several years. We know that the stories of rampant lawlessness due to undocumented immigration are overblown and often flat wrong. What we did not know until a recent report from the University of Colorado is that cities with higher levels of immigration are actually safer places to live.

A new study by sociologist Tim Wadsworth of the University of Colorado at Boulder carefully evaluates the various factors behind the statistics that show a massive drop in crime during the 1990s at a time when immigration rose dramatically. In a peer-reviewed paper appearing in the June 2010 issue of Social Science Quarterly, Wadsworth argues not only that “cities with the largest increases in immigration between 1990 and 2000 experienced the largest decreases in homicide and robbery,” which we knew, but that after considering all the other explanations, rising immigration “was partially responsible.”

To deny that reality and ignore its implications is likely to make life more dangerous all over America, diverting resources away from the fight against violent crime and breaking down the hard-won trust between cops and the communities where they work. Several police chiefs tried to make exactly this point Wednesday on a visit to Washington to talk about the Arizona law, due to take effect in July, and the bad precedent it sets. “This is not a law that increases public safety. This is a bill that makes it much harder for us to do our jobs,” said Los Angeles Police Chief Charlie Beck. “Crime will go up if this becomes law in Arizona or in any other state.”

Common sense rests on the side of law enforcement on this one. Forcing immigrations, even legal ones, into the shadows out of fear of being hassled or deported necessarily reduces tools for law enforcement in carrying out their activities. Aside from the man-hours taken away from preventing violent crimes by checking immigration status, it puts a barrier up between an entire class of citizens and law enforcement. That’s just terrible public policy.

Undocumented immigrants, according to FBI crime statistics, are much more likely to be victims of violent crime than perpetrators. And the incidence of crimes in, for example, Arizona, over the last two years, when a radical crime wave was supposed to be hitting the border, has declined. Declined.

Christopher Dickey concludes:

So, yes, there are pretty compelling data to support the argument that immigrants as such—even presumably “illegal” immigrants—do not make cities more dangerous to live in. But what mechanism about such immigration makes cities safer? Robert J. Sampson, head of the sociology department at Harvard, has suggested that, among other things, immigrants move into neighborhoods abandoned by locals and help prevent them from turning into urban wastelands. They often have tighter family structures and mutual support networks, all of which actually serve to stabilize urban environments. As Sampson told me back in 2007, “If you want to be safe, move to an immigrant city.” [...]

Wadsworth’s research and the recent FBI data reinforce the judgment that the vast majority of immigrants make our cities safer, especially when police know how to work with them, not against them. To blame all immigrants for the crimes committed by a few, and give the cops the job of chasing them for immigration offenses instead of focusing resources on catching the real bad guys, is simply nuts.

Indeed.