Auto theft isn’t much of a problem anymore in New York City. In 1990, the city had 147,000 reported auto thefts, one for every 50 residents; last year, there were just 7,400, or one per 1,100. That’s a 96 percent drop in the rate of car theft.

So, why did this happen? All crime has fallen, nationally and especially in New York. But there has also been a big shift in the economics of auto theft: Stealing cars is harder than it used to be, less lucrative and more likely to land you in jail. As such, people have found other things to do.

The most important factor is a technological advance: engine immobilizer systems, adopted by manufacturers in the late 1990s and early 2000s. These make it essentially impossible to start a car without the ignition key, which contains a microchip uniquely programmed by the dealer to match the car.

Criminals generally have not been able to circumvent the technology or make counterfeit keys. “It’s very difficult; not just your average perpetrator on the street is going to be able to steal those cars,” said Capt. Don Boller, who leads the New York Police Department’s auto crime division. Instead, criminals have stuck to stealing older cars.