The NYT article "Two Sides of a Border: One Violent, One Peaceful" compares the low murder rate in El Paso to the carnage in Ciudad Juarez across the Rio Grande (which, when I crossed the bridge that figures in "No Country for Old Men" in 1980, cost me $0.02 each way). The newspaper mentions various theories, but the article should have mentioned that El Paso has long been famous for an anomalously low crime rate.
Here's an article entitled "The Texas Tranquilizer" from Time's archives, dated October 4, 1971:
By legend Texans are a grandiose breed with more than the natural share of megalomaniacs. But University of Texas Biochemist Earl B. Dawson thinks that he detects an uncommon pocket of psychological adjustment around El Paso. The reason, says Dawson, lies in the deep wells from which the city draws its water supply.
According to Dawson's studies of urine samples from 3,000 Texans, El Paso's water is heavily laced with lithium, a tranquilizing chemical widely used in the treatment of manic depression and other psychiatric disorders. He notes that Dallas, which has low lithium levels because it draws its water from surface supplies, has "about seven times more admissions to state mental hospitals than El Paso." But state mental health officials point out that the mental hospital closest to Dallas is 35 miles from the city, while the one nearest El Paso is 350 miles away—and the long distance could affect admission figures.
But FBI statistics show that while Dallas had 5,970 known crimes per 100,000 population last year, El Paso had 2,889 per 100,000. Dallas (pop. 844,000) had 242 murders, El Paso (pop. 323,000) only 13. Dr. Frederick Goodwin, an expert on lithium studies for the National Institute of Mental Health, doubts that "lithium has these magical properties in the population." Others are not so sure. If lithium does have anything to do with the relative peace in El Paso, what would it do for other cities like New York and Chicago?
By the way, I give reporter James C. McKinley a thumbs-up for using the dreaded V word correctly for once in describing a Mexican neighborhood:
Across the river, the once-vibrant streets of Juárez are dark and gloomy, as residents scurry for home.
My recollection of my evening in Ciudad Juarez in 1980 was that the tourist section was, indeed, "vibrant" -- which, I insist, should only be used to denote a neighborhood with lots of loud live music coming out of the doors of bars (e.g., you can rightly call the French Quarter in New Orleans vibrant, but calling Van Nuys, CA "vibrant" just shows you can't think of anything else to say about it).