The only known common metal that is liquid at room temperature is mercury.
The only country in the world that has a Bill of Rights for Cows is India.
The only active diamond mine in the United States is in Arkansas.
The only lizard that has a voice is the Gecko.
The bloodhound is the only animal whose evidence is admissible in an American court.
The city of Chicago has the only post office in the world where you can drive your car through.
