You have to read the article linked above for some details surrounding that.
This quote was revealing:
Crime Prevention Research Center:
According to a 2013 PEW Research Center survey, the household gun ownership rate in rural areas was 2.11 times greater than in urban areas (“Why Own a Gun? Protection is Now Top Reason,” PEW Research Center, March 12, 2013). Suburban households are 28.6% more likely to own guns than urban households. Despite lower gun ownership, urban areas experience much higher murder rates. One should not put much weight on this purely “cross-sectional” evidence over one point in time and many factors determine murder rates, but it is still interesting to note that so much of the country has both very high gun ownership rates and zero murders.