The Pew Research Center reported last week that the murder rate was cut nearly in half from 7 per 100,000 in 1993 to 3.6 per 100,000 in 2013. Over the same period, overall gun deaths (including accidents and suicides) have fallen by one-third from 15.2 to 10.6 per 100,000.
In spite of this, Pew reports, the American public believes that homicides and gun deaths are increasing in the United States. Those who think violence is getting worse should probably watch less television and look around them instead. The murder rate in the US is currently similar to 1950s levels.
Meanwhile, the number of privately owned guns (and gun commerce in general) in the United States has increased substantially in recent decades.
Source: Firearms Commerce in the US, Annual Statistical Update. (From BATF)
According to the World Bank, here are the homicide rates in the US since 1995:
Here's the homicide rate graphed against total new firearms (manufactured plus imported) in US (indexed with 1995 =100):
Meanwhile, in Mexico, where the US Consulate counsels Americans to not even carry pocket knives in the face of "Mexico’s strict weapons laws." There is exactly one gun store in Mexico. In short, the Mexican experience is a perfect example of the effect of prohibition. A lack of legal access to guns leads to a need for illegal access.
The murder rates in Mexico:
Mexican politicians complain that weapons are easily smuggled from the United States, and that is the source of their problem. But if access to guns is the problem, shouldn't murder rates be much higher in the United States? Moreover, if gun smuggling is such a problem in Mexico, this is just another piece of evidence showing the weakness of prohibition laws in preventing access to the intended target of prohibition.
Naturally, we can't blame everything on gun prohibition in Mexico, nor can we attribute the murder rate decline solely to more guns in the US. But we can say two things for sure: (1) Gun restriction in Mexico has not prevented enormous increases in the murder rate, and (2) increases in gun totals in the US have not led to a surge in the murder rate.