Research a kennel
Pennsylvania requires all kennels who house more than 26 dogs in a calendar year to be registered with the PA Department of Agriculture. This database of kennels and their biannual inspection reports is available for public view. The database also includes boarding kennels and non-profit shelters which do NOT breed dogs.
Each commercial kennel is given a kennel license based on its number of dogs. A K-1 is issued to kennels which have 26-50 dogs while a K-5 is issued to a kennel which have 251-500 dogs. The newly issued CK-6 encompasses those kennels which see more than 500 dogs through its premises during a year.
Clearly, the more dogs a kennel has on its premises the more likely it is to fall into the category of “puppy mill”. A reputable breeder is unlikely house more than 50 dogs a year.
Use the database wisely: breeders are tricky and will often give the public a different kennel name, owner name, or address than their license is registered under. Search all fields in a variety of ways.