Mesa is a city in Franklin County, Washington, United States. The population was 385 at the 2020 census. Originally called Bluff Wells, …Mesa is a city in Franklin County, Washington, United States. The population was 385 at the 2020 census. Originally called Bluff Wells, then Judson, now Mesa was a stop on the Ainsworth to Spokane branch of the Northern Pacific Railroad. It was the stop between Eltopia and Palouse Junction. The station was established in 1883.