Idaho Code § 31-145
Valley county is described as follows: beginning at the southwest corner of section thirty-four (34), township ten (10) north, range two (2) east, on the second (2d) standard parallel north;
Southern boundary. Thence east along the said second (2d) standard parallel, five (5) miles to the center of the North Fork of Payette river; thence northerly along the river to the intersection with the line between townships ten (10) and eleven (11) north; thence east to the ridge dividing the waters of the Salmon and Payette rivers; thence northeasterly along the said ridge and along the ridge dividing Bear Valley creek and Cape Horn creek, to the head of the Middle Fork of the Salmon river;
Eastern boundary. Thence northerly along the said river to the intersection of the fifth (5th) standard parallel north;
Northern boundary. Thence west to the divide separating the waters of the Salmon and Payette rivers;
Western boundary. Thence westerly and southerly along the said divide and the divide between Payette and Weiser rivers, to the line between townships thirteen (13) and fourteen (14) north; thence east to the southwest corner of township fourteen (14) north, range three (3) east; thence south twelve (12) miles to the southwest corner of township twelve (12) north, range three (3) east; thence west three (3) miles to the northwest corner of section three (3), township eleven (11) north, range two (2) east; thence south twelve (12) miles, to the place of beginning.
County seat-Cascade.
Idaho Code § 31-145