Those now densely populated states harbour a killer animal which claims 200 deaths a year and over a million traffic collisions.
The USA’s most dangerous mammal is the deer.
Now wildlife scientists are suggesting re-introducing cougars which would hunt down the deer and prevent thousands of injuries and 155 deaths over 30 years.
In South Dakota, which was recently re-colonised by cougars, there has been a 9% drop in deer-related car crashes over eight years.
The downside is that they would occasionally kill a human being. So the balance is this: having on average less than one person a year killed by cougars but preventing 5 deaths a year and 700 injuries from deer vehicle collisions.
So an interesting dilemma about a biological control method.