Dictionary.net

In the United States, trademark ownership arising from "first use" of a mark. First use can be established by actual use or by application with the Patent and Trademark Office (PTO) for registration on an intent to use basis. If the same mark has been in use by different businesses in different parts of the country without causing customer confusion, the mark may be owned by both businesses in their respective regions. If the mark owners then come into conflict in another part of the country, ownership for the purpose of that region will be determined according to who was the first user and which business could most likely consider the region as a natural zone of expansion.