A: Massive urbanization. America changes from mainly farmers to mainly city dwellers. Massive immigration of European groups that had been suppressed for generations by landlords, the government and the church. A small percentage of some immigration groups react to their newfound "liberation" by becoming criminals. The dislocations of WWII were follwed by the easy money of bootlegging.
B: The murder rate from 1870 to 1905 was slightly under or slightly over 1 per 100,000. During this time anyone, balck, white, immigrant, a 14 year old, etc. could buy a firearm anywhere and anytime. If "guns cause murder" as the anti-freedom groups say, why was the murder rate so low when anyone and everyone could buy firearms? It is self-evident that whatever factors increase the murder rate, the open and free sale of firearms is NOT one of them.
C: If "poverty causes crime" as the left-wing anti-guns groups say, why was there a 45% DECREASE in murders during some of the worst years of the great depression?
D: Prohibition repealed. The murder rate DECREASES by 50% between 1933 & 1958. During this time, any adult could buy any kind of firearm, even mail-order purchase of firearms.
E: The landmark 1968 Gun Control Bill is passed. Congress promises the American people this bill will end gun violence in America.
F: The "drug culture" takes hold and the "drug wars" start.
G: Ten million soldiers return to America and leave the armes services after WWII. Many also return after the Korean War. Many undreds of thousands bring back "souvenirs" of every kind, including fully automatic machine guns. Millions of military surplus firearms come into America, literally by the shipload and are sold on the open market. If "guns cause crime" as the gun control groups contend, there should have been and explosion of murder during this time.
H: The 1960 to 1980 period is a mirror image of 1905 to 1933. This time it was the massive urbanization of the Black population, plus renewed massive immigration. As in the 1905-1933 period, a small percentage of the newly "liberated" groups turned to professional crime. The crime family bootleg wars were duplicated by the drug wars. The black drug war criminal gangs of today, like the Sicilian, Italian and Irish gangs of the 1920's will eventually settle down, a process that appears to have already started in the 1980's. The decriminalization of "diet pills" would probably lower the murder rate. Not to the same degree as the repeal of prohibition, but it would help