The region of the Platte Purchase includes the following modern counties within its bounds: Andrew (435 square miles, 1127 km), Atchison (545 square miles, 1412 km), Buchanan (410 square miles, 1062 km), Holt (462 square miles, 1197 km), Nodaway (877 square miles, 2271 km), and Platte (420 square miles, 1088 km).