In his book, When Brute Force Fails, [Mark] Kleiman explains that a number of historical and social factors combined to create the crime boom of the latter part of the 20th century, the biggest factor was demographics."People commit most of their crimes between the age of 15 and 30, and so periods of time when there are more people in that age range have more crimes," Kleiman explains. "In addition, a particularly big birth cohort like the Boomers, and to some extent, the Echo Boomers, tend to have a higher individual per-person crime rate."This, Kleiman says, also happens to explain some of the cultural upheaval of the 1960s. "That's why the baby bombers brought us sex, drugs and rock and roll while the 1950s teenagers didn't. The 1950s teenagers were outnumbered by their elders, the '60s teenagers outnumbered their elders."
The implication behind a pure causal link between violent crime, especially, and employment has always struck me as weird. It presumes that violent criminals are actually just people who can't get a job. Some of them surely are. But it takes more to put a gun to someone's face than the simple absence of a 9 to 5.