In the US, the crime rate is down. Significantly. While crime had once soared sharply in the late 1960s and early 1970s (does anyone remember the days of the “crack epidemic”), it has since declined steeply since 1993. The marked change in a trend that has an immediate and profound impact on many lives has astonished many observers.

In a 2009, Washington Post article, experts expressed bafflement:

Violent crime has plummeted in the Washington area and in major cities across the country, a trend criminologists describe as baffling and unexpected.

The District, New York and Los Angeles are on track for fewer killings this year than in any other year in at least four decades. Boston, San Francisco, Minneapolis and other cities are also seeing notable reductions in homicides.

“Experts did not see this coming at all,” said Andrew Karmen, a criminologist and professor of sociology at the John Jay College of Criminal Justice in New York.

There are lots of hypothesis around why the crime rate has steadily declined over the decades. Some focus on a causal link between legalized abortion and the drop in crime during the 1990s. Another theory suggested stiff laws like the Three Strikes Law, (which sentenced people to life imprisonment if they committed a third offense) could have also had an impact. Research on both these theories has not been definitive.

But what seems to me an interesting and somewhat unexplored phenomena has been the growing popularity of plastic – and how are increasingly reliance on plastic and cards has robbed many criminals of an incentive to “stick you up”.

In the old days, a purchase of groceries, gas, booze or an expensive stereo meant you needed to carry around large wads of cash. Sure you could pay by cheque, but for many shopping adventures, that simply wasn’t the easiest way of doing things. Big wallets could mean big payouts for criminals looking for an easy score and the common nature of carrying cash meant that odds were you’d walk away with some money (and potentially more than just some) should you rob your victim.

As always the risk of ending up in jail needed to be outweighed by the potential rewards of a successful caper. In the mid-20th century, it could be argued that this was indeed the case.

These days it’s much harder to stick someone up. As Slate recently detailed in an article, you might walkaway without a penny:

Last September, Melvin Jesse Blain tried to rob a South Carolina bank. When the teller told Blain she had no cash, he thanked her and left. The previous July, two men tried to rob a pizza delivery woman in Troy, N.Y. When they discovered she had no cash, they took the pizza instead. On Nov. 1, police in Beaufort, S.C., arrested a man who had tried to hold up a Smoker’s Express and an IHOP but left with nary a dollar.

Then there’s the old stick-up of an everyday citizen. Sure you can try and rob a passer-by, but usually the most it will likely earn you is $10 or $20 and maybe their blockbuster rental card. Doesn’t really seem worthwhile when you’re risking month in prison – that is unless your so strung out and desperate that the reward of $20 is worth spending months in the slammer.

An even more interesting question isn’t just how crime rates may be effected by a cashless economy, but how drug deals may also be significantly impacted. What happens when we reach a point a few decades into the future when there is no cash? All transactions (from the purchase of a jujube to a Mercedes) will be done via debit or credit card. Imagine the effects of this on the drug buying community (not to mention organized crime). All of the sudden, all purchases are tracked electronically. The death of the anonymous dollar could make purchasing pot, heroin or cocaine that much more difficult. No longer will a buyer be able to stroll up to a dealer on the corner and pay a $20 cash for some weed. Now he’ll have to bring a credit card with him. The dealer will need a card machine. When the purchase is made a transaction record will exist. This could potentially be easily tracked by law enforcement officers and could also be strong evidence in court prosecutions.

For dealers, new rules would make it more difficult and hence more expensive to launder and hide drug purchases. Costs for drugs would undoubtedly increase to reflect this.

At the same time, it is likely demand for illegal drugs would likely decline as it became apparent to both new and old users that purchasing drugs that could be easily traced to one’s credit card would be far riskier than it had once been with cash.

Such factors could have a potentially enormous impact as our small and ubiquitous pieces of plastic, effectively reorganizing the international drug market and make it harder and harder for criminals to rob victims using just brawn rather than brains as well.