Source: Bigstock

Not surprisingly, the worst homicide rates in 2017 were in highly black cities, such as St. Louis (65.8 homicides per 100,000), Baltimore (55.8), New Orleans (40.1), Detroit (39.7), Cleveland (33.7), Kansas City (31.2), and Memphis (30.6).

The most homicidal big city without an above-average percentage of blacks is Las Vegas (36.7, or a still-high 27.0 when leaving out the Mandalay Bay massacre).

In sharp contrast to heavily black cities, towns near the Mexican border were exceptionally murder-free in 2017, such as San Diego (2.4), Tucson (3.2), and El Paso (2.8).

El Paso has been famous for its calm citizenry for generations. A 1971 article in Time, “The Texas Tranquilizer,” attributed the low murder rate in El Paso to the high levels of lithium in its well water.

On the other hand, Ciudad Juárez across the Rio Grande is notorious, even in Mexico, where the murder toll was about 29,000 in 2017, for its hideous violence.

My guess is that the extreme criminality in Mexico since late 2006 has, perhaps surprisingly, lowered the crime rate in Mexican-American neighborhoods in the U.S. Back in the 1970s, when America was liberal about not punishing crime while Mexico was a one-party dictatorship, it made sense for bad guys to ply their trade north of the border. Today, in contrast, there is ample lucrative employment for killers in chaotic Mexico, so that drains American border towns of their worst denizens.

Outside of Las Vegas, the biggest increase in absolute numbers of homicides was in Columbus, Ohio, where killings increased from 106 to 143. While it has a fairly sizable black population (28 percent), Columbus is not really a Rust Belt town like Detroit or Cleveland. It’s a sprawling All-American city where the U.S. national soccer team plays its home matches against Mexico to get away from Mexican-American fans rooting for Mexico.

Ironically, Columbus has been targeted by Mexican heroin smugglers as a low-key base of operations. In recent years, Mexican heroin retailers have tended to avoid black cities as too dangerous and attention-getting.

But perhaps the heroin epidemic has finally turned into a shooting war, making Columbus the new Colombia?