If you're looking for the oldest breed of dog in North America, you'll have to look quite close to the ground. If you're looking closer to home, the oldest extant dog breed to originate in the United States was probable the American foxhound.
While the exact origins of the Chihuahua are unclear, it's known that they were bred in North America, in what is now Mexico. The earliest records of the breed predate 1530 and were found in Pyramids of Cholula, but it's likely that the Chihuahua is even older. These dogs were sacred in pre-Columbian times but were also commonly kept as pets by the upper classes. They may have been exported to Europe by Christopher Columbus. Today's Chihuahuas are smaller than those of the past, perhaps a result of introducing Chinese Crested bloodlines into the breed.
About the Chihuahua
Chihuahuas are famous for being the world's smallest breed of dog. These diminutive dogs tend to measure 6 to 9 inches to the shoulder and should not weigh more than 6 pounds, according to the American Kennel Club. They come in both long and short coats. AKC standards allow any coat color, be it solid, marked or splashed. Common colors include fawn, chestnut, white, parti-colored, and black and tan. While small, they still require plenty of exercise and should be taken on daily walks and given plenty of playtime. Long-haired varieties will need daily grooming with a soft-bristle brush. Although a smooth-coated Chihuahua won't need as much grooming, his fur will still need the odd brush or wipe over.
An Ancient Breed
The very oldest known domesticated dog in North America lived roughly 9,400 years ago. Bone fragments belonging to one such dog were found in Texas by researchers from the University of Maine. Not much is known about this type of dog, but it would have weighed around 30 pounds and wound up as someone's dinner.
The American Foxhound
Originating in Virginia and Maryland during the 1700s, the American foxhound is probably the oldest American dog breed that still exists today. In 1650, a pack of hounds were brought to the United States from Europe, and these dogs were the foundation stock for the foxhound breed. They were developed as field hounds for hunting and competition and were first recognized as a breed by the American Kennel Club in 1886.