New York’s plan to add 800 police officers raises a question every city has been asking since crime began to fall in the 1990’s: How many officers are enough?, says the New York Times. “There’s no formula for that,” said Jerome Skolnick, a law professor at New York University. “Nobody knows what the precise proportion should be.” The size of the police force a city needs may be affected by everything from poverty to geography to population density. New York City, with 8.1 million residents and 309 square miles, is one of the nation’s most thoroughly policed cities. It has 36,450 officers – 4.5 for every 1,000 residents, and 118 per square mile.
The police are spread much more thinly in the second most populous city, Los Angeles, which has 3.8 million residents, 469 square miles and 9,311 police officers–2.4 officers for every 1,000 residents and only 20 officers per square mile. Determining the proper size of a police force is an imprecise exercise. Washington has nearly 7 officers for every 1,000 residents, nearly three times that of Los Angeles, and for decades has had among the highest rates of violent crime of any large city. “It would be very nice if we had independent estimates of what adding a cop would do to the crime rate in other places than New York,” said law Prof. Franklin Zimring of the University of California-Berkeley. “You can’t do that. The science isn’t there.”