An Arizona section of the US-Mexico border fence

A US government study points to an overall decrease in US border crime between 2004 to 2011, further indicating that fears of a "spillover" effect from Mexico's war against organized crime may be unfounded.

The report, released by the United States Government Accountability Office (GAO) earlier this month, found that the average rate for both violent and property crimes had dropped in the US Southwest border states. Arizona saw the most significant decline, of 33 percent over the seven-year time period. Other decreases were seen in Texas (30 percent), California (26 percent), and New Mexico (eight percent from 2005 onward).

Significantly, violent crime was found to be lower in border counties than in non-border counties for all the years examined in three out of the four states -- California, New Mexico and Texas -- with Arizona the only exception.

The GAO also reported that assaults against Border Patrol agents decreased between 2008 to 2012, to levels 25 percent lower than in 2006. Officials from 31 of the 37 state and local law enforcement agencies interviewed by the GAO stated that they had not observed violent crime from Mexico regularly spilling over into the US, although many said they were still concerned about safety levels in the region.

Local law enforcement officials told the GAO that increased law enforcement personnel and new infrastructure may have contributed to the declining crime rates. Recent US federal efforts -- including technical assistance to Mexico under the 2008 Merida Initiative and $600 million put towards border security in 2010 -- have also aimed to curb violence in the region.

InSight Crime Analysis

Concerns have long existed about the extent to which Mexico's conflict may affect security dynamics in the US border states. Several incidents, involving Mexican nationals carrying out violent attacks in relation to the drug trade on US soil, have only served to feed such fears.

However, available data has generally failed to support these concerns. Figures from the Federal Bureau of Investigations (FBI), for example, show that violent crime in Arizona declined from 532 incidents per 100,000 inhabitants in 2000, to 408 in 2010. An analysis by Austin-based newspaper the Statesman found that, despite the release of a government-sponsored report warning of escalating violence in Texas, the combined number of murders in the state's 14 border counties fell by 33 percent between 2006 and 2010. The GAO's most recent study further supports the interpretation that claims of rampant "spillover violence" in the US border region have been mostly exaggerated.