Texans will be quick to tell you that their state is one of the most armed in the country. Tales of rifles on gun racks in trucks abound. This might be because civilians helped overwhelm a murderous sniper when the local police weren’t quite equipped to deal with the tactical problem.
Some fifty years ago (August 1, 1966) an engineering student named Charles Whitman climbed the 307 foot tall limestone landmark on the University of Texas grounds and began shooting innocent wanderers. Firearms that local police carried at the time weren’t able to respond at that distance… local civilians were enlisted to bring the man down. Before the incident was concluded, 17 people were killed and over 30 were wounded.
According to the Washington Post , 25 mass public killings happened in the fifty years before UT… 149 have happened since. Of course, on 9-10 November 1938 ninety one people were killed in Germany (Kristalnacht). Although accounts differ, Hitler went on to kill 20 million. Stalin also killed between 2 and 3 million of his own. In Ukraine on June 23, 1919 alone, 45 people were killed, countless raped, though estimates of fatalities due to pogroms in Ukraine in the few years after 1919 range in the multiple tens of thousands. Ten years later, more than 3 million died in Ukraine due to forced starvation (Holodimir) thanks to Soviet Russia. Would an armed populace helped prevent these mass killings?
Mao Tse Tung managed to kill between 20 and 45 million of his citizens due to agricultural reforms initiated during the 1958-1961 Cultural Revolution. Would Chinese citizens have prevented these policies under a Chinese “2d Amendment?”
In any event, you can find a pretty detailed overview of Texas and 2d Amendment dynamics here: https://www.tribtalk.org/2016/01/08/how-obamas-executive-actions-affect-texas-gun-politics/