Post Falls is a city in Kootenai County, Idaho, United States. It is the gateway city to Northern Idaho off Interstate 90, just west of Coeur d'Alene, and east of Spokane, Washington. The population is an estimated 44,798 in 2023 according to the U.S. Census Bureau, making it Idaho's ninth-largest city and the second largest city in North Idaho behind Coeur d’Alene.