Mule-drawn wagon has GPS, toilet ZUMBRO FALLS, Minn., June 13 (UPI) -- A Minnesota couple who began traveling by mule-drawn wagon a few years ago said they are taking it on a cross-country trip. Warren and Mary Veien of Zumbro Falls said they will set out next week for a cross-country trip in their mule-drawn wagon, whose amenities include a GPS, a frontal brake system, a charcoal grill, beds, seats taken from pickup trucks and a Port-o-Potty, WCCO-TV, Minneapolis, reported Wednesday. "They always say a mule, if you can rub their forehead, then you can do most anything with 'em," Warren Veien said. He said the only thing his mules won't do is go near semi trucks, so they stick to traveling on gravel roads, away from the larger vehicles. The couple said they will be accompanied on their cross-country excursion by 25 other covered wagons forming a "wagon train."