Puppy mills have been inhumanely breeding and selling dogs for decades

Although the federal government regulates most breeders who sell puppies online and to pet stores, the minimal standards imposed on breeders do not promote responsible breeding or ensure healthy puppies.
It's legal for licensed breeders to own 1,000 or more dogs, keep them in very small cages for their entire lives and breed them as often as possible.
The standards set by the government are not meant to ensure that the dogs have the good lives they deserve; they only require the bare minimum of care. Plus, there are only a few inspectors in each state for hundreds – sometimes thousands – of licensed breeding facilities.
Nearly all pet stores that sell puppies are supplied by mills. More and more communities are banning the sale of mill-bred pets in stores, but many Americans are still unaware of the connection between pet stores and puppy mills.

Which pet stores sell puppies supplied by puppy mills?

Nearly 100% source from Puppy Mills. The estimated number of puppy mills in the U.S. that supply to pet stores or sell online: 10,000+
Like pet stores, most websites selling dogs are mill-bred pets, marketing puppies as well-bred and lovingly raised. No matter how convincing these websites are, never buy a pet online.
Classified Ads. For decades, classifieds have been the first place that puppy buyers go to look for a new pet. Irresponsible breeders tap into this market easily by placing classified ads on websites like Craigslist. Beware of any ad that lists several breeds for sale, and if the breeder can’t provide proof of breed origin and authentication documents do not buy the dogs and puppies.

Don't buy dogs from pet stores or on the Internet. Adopt instead.
Spread the word: Teach others about puppy mills.
Choose adoption. About 800,000 animals are killed in U.S. shelters annually, simply because they don't have homes. When you adopt, you're not only refusing to support puppy mills, you're saving a life and giving an animal in need the second chance he or she deserves.
It is estimated that up to 25 percent of dogs looking for homes through shelters and rescue groups are purebred.
Types of pets found in shelters and rescue groups: Young, purebred, old, house-trained, mixed-breed, adorable, well-mannered, puppies, healthy, kittens.