Turns out I was wrong about the 300nm qualifier: as others have said it depends on the jurisdiction.
FAR part 61 says "(i) One cross-country flight of not less than 300 nautical miles total distance, with landings at a minimum of three points, one of which is a straight-line distance of at least 250 nautical miles from the original departure point. However, if this requirement is being met in Hawaii, the longest segment need only have a straight-line distance of at least 150 nautical miles"
