This one is very interesting indicating that the majority of the country is NOT impacted by Narco Violence.
http://www.gov.harvard.edu/files/CosciaRios_GoogleForCriminals.pdf
http://www.csmonitor.com/World/Americas/Latin-America-Monitor/2012/1031/Mexico-How-far-do-drug-gangs-reach
http://www.gov.harvard.edu/files/CosciaRios_GoogleForCriminals.pdf
http://www.csmonitor.com/World/Americas/Latin-America-Monitor/2012/1031/Mexico-How-far-do-drug-gangs-reach