Which state has jurisdiction over my debt?

The question is who has jurisdiction over you.  In this case, as you reside in Washington but the claim arose out of activities you undertook in Nevada, I think either state would have jurisdiction. The same statute of limitations, which would probably be Nevada's unless there is a contrary provision in the promissory note, would be applied by either court.  States apply their own procedural law to disputes, but for substantive matters generally (I'm oversimplifying) apply the law of the state or other jurisdiction (could be a foreign country) with the most connection to the controversy.  Thus, it is not at all unusual for a court in New York, for example, to apply California law to a dispute. You should know that many states have rules that limitations periods are tolled if a defendant leaves the jurisdiction for a substantial period of time.