You need to carefully evaluate the market presence of both companies in the US, especially any cross border advertizing by the Canadian company, e.g., advertizing on a broadcast in Windsor, Canada that is received in Detroit, Michigan. If, as you suspect, there is no contact with the US by either company, you should seek to register the trademark in the US Patent and Trademark Office. However, be aware that, since you are selling a competing product and are aware of these companies, if you use the name in your website domain name, either one or both can seek to have the domain name taken away from you. The best course of action is to adopt a "clean" name that is not in use by a competitor or similar to such a name.
Answered on Jan 03rd, 2014 at 3:51 PM