Stephen Dubner

Alberta is just over 250,000 square miles. That's roughly the same size as Texas, where there are many rats. But Alberta says it does not have a single breeding population of rats. Karen Wickerson gives some credit to the public.

Wickerson told us that she gets about 500 reports of rat sightings a year, but that only around 30 of them are legitimate. How can this be? Apparently, when rats are rare, a lot of people don't even know what a rat looks like.

Wickerson told us that she gets about 500 reports of rat sightings a year, but that only around 30 of them are legitimate. How can this be? Apparently, when rats are rare, a lot of people don't even know what a rat looks like.

Wickerson told us that she gets about 500 reports of rat sightings a year, but that only around 30 of them are legitimate. How can this be? Apparently, when rats are rare, a lot of people don't even know what a rat looks like.

So what does it take to be essentially rat-free? Alberta has run a strict anti-rat program since the 1950s. The Norway rat was migrating then in great numbers from the eastern part of Canada, and farmers out west saw the potential for crop damage.

So what does it take to be essentially rat-free? Alberta has run a strict anti-rat program since the 1950s. The Norway rat was migrating then in great numbers from the eastern part of Canada, and farmers out west saw the potential for crop damage.

So what does it take to be essentially rat-free? Alberta has run a strict anti-rat program since the 1950s. The Norway rat was migrating then in great numbers from the eastern part of Canada, and farmers out west saw the potential for crop damage.

Among rat people, Alberta is famous the way Pine Valley is famous among golf people as a remote and sanctified place, almost too good for this world.

Among rat people, Alberta is famous the way Pine Valley is famous among golf people as a remote and sanctified place, almost too good for this world.

Among rat people, Alberta is famous the way Pine Valley is famous among golf people as a remote and sanctified place, almost too good for this world.

So how did Karen Wickerson enjoy her visit to the super ratty jurisdiction of New York?

So how did Karen Wickerson enjoy her visit to the super ratty jurisdiction of New York?

So how did Karen Wickerson enjoy her visit to the super ratty jurisdiction of New York?

As a New Yorker, I am, of course, proud that we keep coming up with new ways to entertain visitors. But we should talk about the garbage.

As a New Yorker, I am, of course, proud that we keep coming up with new ways to entertain visitors. But we should talk about the garbage.

As a New Yorker, I am, of course, proud that we keep coming up with new ways to entertain visitors. But we should talk about the garbage.

That's coming up after the break. I'm Stephen Dubner and this is Freakonomics Radio. When we first set out to make this series on rats, we were inspired by what you might call a foundational text. A book called Rats, Observations on the History and Habitat of the City's Most Unwanted Inhabitants by Robert Sullivan.

That's coming up after the break. I'm Stephen Dubner and this is Freakonomics Radio. When we first set out to make this series on rats, we were inspired by what you might call a foundational text. A book called Rats, Observations on the History and Habitat of the City's Most Unwanted Inhabitants by Robert Sullivan.

That's coming up after the break. I'm Stephen Dubner and this is Freakonomics Radio. When we first set out to make this series on rats, we were inspired by what you might call a foundational text. A book called Rats, Observations on the History and Habitat of the City's Most Unwanted Inhabitants by Robert Sullivan.

I remembered reading an excerpt of the book in the New York Times Magazine when it was published in 2004. And then recently, a dear old friend of mine died and I inherited some of his books. Rats was one of them. My friend, Ivan, was the kind of reader who likes to underline interesting passages of a book as he goes.