“DHS data gives the number of illegal immigrants apprehended in each border patrol sector”

It should probably be kept in mind that the DHS does not catch every illegal immigrant, and the rate that it does (and how changes in border patrol operations affect the caught vs. uncaught rate as coyote tactics change) are likely to be highly variable.

There is a constant state of flux of illegal immigrant population, for example there has recently been a large effort to deport criminal illegal immigrants:

“In fiscal year (FY) 2010, U.S. Immigration and Customs Enforcement (ICE) removed more illegal aliens than in any other period in the history of our nation. ICE removed more than 392,000 illegal aliens-half of them, more than 195,000-were convicted of crimes, including murder, sex offenses and drug violations.”

Moreover, it is believed that the financial crisis decreased the number of people seeking to enter the US illegally.

- California built a fence a while back, so coyotes and traficantes increasingly moved to Arizona, New Mexico, & Texas the last decade.

- I believe there was a power vacuum created when one cartel fell, the war was over there territory in the middle, with violence centered there.

1) not explaining the other factors that played into the rise in violence in Mexican states bordering AZ and Texas (namely, conflicts among the Gulf, Juarez, Sinaloa and —more recently— Zeta drug trafficking organizations), and

2) not using data through 2010 (which show that violence jumped suddenly in Baja California in 2008, and then fell just as suddenly in 2009… regardless of California’s gun laws).

Does the graph on gun-related homicides give any information to this question? I am not into this, but I do not think so. If one wants to commit a murder, he/she will substitute the better available firearms for poison & other weapons. That is obvious – but does the availability of guns indeed increase overall rates of murder/violence?

The citation of the paper suggests that overall rate of homicides did also rise – ok, that would be an answer to the question. But the graph is not so interesting at all… or do I miss an important fact?

“The experiment:”
“Collating the latest homicide data available from the UN Office on Drugs and Crime with SAS [Small Arms Survey] data creates a dataset of 145 UN countries.”

“The results:”
“The graph below highlights the lack of correlation between GPC [guns per capita] and homicide rates (all rates in incidents per 100,000 population). Spearman’s value is -0.10: As GPC increases, homicide rates decrease, albeit weakly.”

From:
http://pajamasmedia.com/blog/united-nations-ignores-its-own-data-to-promote-gun-ban/?singlepage=true

Since they focused on Texas and Arizona, so will I.

According to the FBI, Texas has seen a steady decline in the rate of violent crime in general (9%), and murder rates in particular (12%), from 2004 through 2009.

Arizona has seen even more impressive reductions over the same span of time. While both the rate of violent crime in general, and murder rates in particular went up in 2005, over the span of 2004 to 2009, the rate of violent crime decreased 19% and the murder rate dropped by 25%.

For comparison, the US national data over the same period showed a 7% drop in violent crime rates and a 9% drop in murder rates.

Totally agree!