Lah-Toh County was created by the Idaho Territorial Legislature in 1864 with Coeur d'Alene as its county seat. The name is Nez Perce for "the place of pine trees and sestle". The county was abolished in 1867, although sources disagree whether the area was absorbed by Nez Perce County or Kootenai County. It is most likely Kootenai since Coeur d'Alene serves as that county's county seat.
The county was re-established in 1888 with different boundaries as Latah County.