Idaho Code § 31-104
Adams county is described as follows: beginning at a point on the boundary line between the states of Idaho and Oregon, the same being the middle of the center channel of Snake river, three thousand nine hundred sixty (3,960) feet in a southwesterly direction from the mouth of Wildhorse river;
Southern boundary. Then in an easterly direction fifteen and one-half (15 1/2) miles to a point one-half mile east of the west quarter corner, section six (6), township seventeen (17) north, range two (2) west; thence south about twelve (12) miles to the intersection of said line with Cow creek; thence southeast down the center line of Cow creek to its confluence with the Weiser river; thence south across the Weiser river to a point five hundred (500) feet east of the north quarter corner of section twenty-nine (29), township fifteen (15) north, range two (2) west; thence east about three and three-quarters (3 3/4) miles to a point one thousand three hundred twenty (1,320) feet east of the northwest corner of section twenty-five (25), said township and range; thence south eight and one-half (8 1/2) miles to a point one thousand three hundred twenty (1,320) feet east of the west quarter corner of section one (1), township thirteen (13) north, range two (2) west; thence in a southeasterly direction six and one-half (6 1/2) miles to a point one thousand three hundred twenty (1,320) feet south and one thousand three hundred twenty (1,320) feet east of the west quarter corner of section twenty-four (24), township thirteen (13) north, range one (1) west; thence east (1911, ch. 31, section 2, pp. 67, 68) to the summit dividing the waters of the Payette and Weiser rivers;
Eastern boundary. Thence along said divide in a northerly direction to a point on said divide known as Big Rock Flat, where the waters flow into the Little Salmon; thence in a northeasterly direction on a low divide separating the waters of the Little Salmon and Payette rivers to a point east of the northern point of Little Salmon Meadows;
Northern boundary. Thence west to the Little Salmon river; thence down the Little Salmon river to a point east of the point where the section line between sections six (6) and seven (7), township twenty-two (22) north, range one (1) east, intersects said meridian; thence west to the middle of the main channel of Snake river (R.C., section 23w), the same being the boundary line between the states of Idaho and Oregon;
Western boundary. Thence in a southerly direction following said boundary line between said states of Idaho and Oregon, to the point of beginning (1911, ch. 31, section 2, p. 68).
County seat-Council.
Idaho Code § 31-104