Platte County is a county located in the northwestern portion of the U.S. state of Missouri and is part of the Kansas City metropolitan area. As of the 2020 census, the population was 106,718. Its county seat is Platte City. The county was organized December 31, 1838, from the Platte Purchase, named for the Platte River. The Kansas City International Airport is located in the county, approximately one mile west of Interstate 29 between mile markers 12 and 15. The land for the airport was originally in an unincorporated portion of Platte County before being annexed by Platte City, and eventually Kansas City.

The Kansas City metropolitan area is a bi-state metropolitan area anchored by Kansas City, Missouri. Its 14 counties straddle the border between the U.S. states of Missouri and Kansas. With 8,472 square miles (21,940 km2) and a population of more than 2.2 million people, it is the second-largest metropolitan area centered in Missouri and is the largest metropolitan area in Kansas, though Wichita is the largest metropolitan area centered in Kansas. Alongside Kansas City, Missouri, these are the suburbs with populations above 100,000: Overland Park, Kansas; Kansas City, Kansas; Olathe, Kansas; Independence, Missouri; and Lee's Summit, Missouri.