What is a Common Law Trademark?

[Doug]

If I want to claim a common law trade mark and I get one order in every state of the union from an online national campaign, does that give me national wide common law trade mark rights? Assume I am the first to market with the name. Also assume the industry is hugh in every State: like millions of potential and actual users; and other competitors are thousands of times bigger than my sales volume in each State. Therefore, my sales volume has very small penetration in each State. Also assume most people that are interested in the product would not associate my mark with the product. If one sale per State is too small of a volume to get a common law trade mark, what would be an acceptable volume for me to establish a common law mark?