Lewis County is a county located in the north central region of the U.S. state of Idaho. As of the 2010 census, the population was 3,821, making it the fourth-least populous county in Idaho. The county seat is Nezperce, and Kamiah is the largest city. Partitioned from Nez Perce County and established in 1911, it was named after the explorer Meriwether Lewis.

Lewis county is not organized, contact morgan@idahodems.org for more information.