Contact AKC (American Kennel Club), and ask them. They will know how many registered dogs, particularly pure breds. If they cannot tell you, or won't because of privacy reasons, they may be able to point you in the right direction. Please keep in mine that they will not have an exact number, because many people do not register their dogs. Also, some people have mixed breeds, and you don't know which breed category they will be counted in.
the welsh springer spaniel is the most uncommon breed in the us
There is not a specific dog breed that is smarter than any other dog breed in the world than there is in the USA, but the smartest dog breed are poodles.
The US.
We can't answer your question, because you do not give us a breed of dog. Please restate your question
grey hound
500,000 to 1,000,000
bulldog
Boston terrier
Labrador Retriever
yorkie
grey hound
The oldest dog breed in Asia is the Shar-pei. This was a fierce breed bred for hunting and guarding. The almost went extinct but due to a population surge in the US in the 1970's the breed has made a remarkable come back.