Astronomer Isaac James surveyed this corner of Arizona, Nevada, and Utah in 1870 and set it 111.51 chains too far north — a chain is 66 feet, so his marker landed about 1.4 miles off the true 37th parallel. The error stood for over a century until the Bureau of Land Management and three states’ surveying associations re-monumented the corner with sub-centimeter GPS, dedicating the correction at a ribbon-cutting in February 2017. It’s reachable only by a hike into the desert outside Mesquite, Nevada.