 Earlier placements in 1931 involved geographers balancing a cardboard cutout of a region on a needlelike point to find its center to establish a spot ""6 miles west of Balta, Pierce County, North Dakota"" at 48⁰ 10′north, 100⁰ 10′west, The 15-foot (4.5 m) field stone obelisk in Rugby, North Dakota (~15 miles or 25 km away) marks an erroneous claim unsupported by evidence.The Great Plains is the broad expanse of prairie and steppe which lies east of the Rocky Mountains in the United States and Canada.The narrow plains in the Mexican coast and the savannas of the Mississippi are analogous to, respectively, the Patagonian steppes and the pampas of the Piranha, Paraguay, and Rio de la Plata.