The number of states issuing concealed carry permits has increased by 10 in the past 10 years, according to a report issued by the U.S. Government Accountability Office on July 17.

The number of shall-issue states increased from 29 in June 2002 to 39 by March 2012, and the number of states that do not require a permit to carry a concealed weapon increased from one in June 2002 to four in March 2012. The number of may-issue states dropped, however, from 13 in 2002 to 10 in 2012.

In the 2012 breakdown of concealed carry gun permits, the GAO counts four states - Alaska, Arizona, Rhode Island, and Wyoming - in two categories, "so the total number of states and the District of Columbia adds to 55 in this analysis," the GAO explained.