Will Cities Ever Outsmart Rats?

It used to be said that there was one rat for every person in New York City. If that were true, there would be as many as 8.6 million beady-eyed rodents lurking in the streets, alleys, and tunnels of Gotham. That claim has been debunked, but good luck finding comfort in the more modern estimate that New York is a city of a mere 2 million rats.

The thing is, no one really knows how many rats there are. Not in New York City, nor Washington, D.C., nor Chicago—all three of which rank among the most rodent-infested cities in the U.S. Even the best numbers available are educated guesses, often based on surveys about calls to 311. It’s even more challenging to understand how rats move or anticipate where they will wreak havoc next. But cities have entire teams dedicated to controlling the rat population, and for good reason. The rodents sneak into buildings and subways, nibbling on trash, chewing through cables, and spreading nasty diseases, often while remaining out of sight. Despite the best efforts to deploy traps, poison, and—yes—even cats, the rodents persist.