The region of the Platte Purchase includes the following modern counties within its bounds: Andrew (435 square miles, 1127 km2), Atchison (545 square miles, 1412 km2), Buchanan (410 square miles, 1062 km2), Holt (462 square miles, 1197 km2), Nodaway (877 square miles, 2271 km2), and Platte (420 square miles, 1088 km2). It also includes the northwest suburbs of Kansas City, a small area of Kansas City proper, the cities of St. Joseph and Maryville, Missouri, as well as Kansas City International Airport and almost all of Missouri's portion of Interstate 29, save the small portion which runs concurrently with Interstate 35 in Clay County.