Idaho Code § 31-105
Bannock county is described as follows: beginning at the intersection of the township line between townships four (4) and five (5) south, with the Snake river;
Western boundary. Thence down the Snake river southwesterly to the mouth of Portneuf river; thence up the Portneuf river to the intersection of the Portneuf river with the west boundary of section eight (8), township six (6) south, range thirty-four (34) east Boise meridian; thence south four and one-quarter (4 1/4) miles to the southeast corner of section thirty-one (31), township six (6) south, range thirty-four (34) east Boise meridian; thence west to the northeast corner of section six (6), township seven (7) south, range thirty-four (34) east, Boise meridian; thence south four (4) miles to the southeast corner of section nineteen (19); thence east one (1) mile to the northeast corner of section twenty-nine (29); thence south four (4) miles to the southeast corner of section eight (8) township eight (8) south, range thirty-four (34) east Boise meridian; thence east two (2) miles to the northeast corner of section fifteen (15); thence south two and one-half (2 1/2) miles to the east quarter (E1/4) corner of section twenty-seven (27); thence east one (1) mile to the east quarter (E1/4) corner of section twenty-six (26); thence south one and one-half (1 1/2) miles to the southeast corner of section thirty-five (35), township eight (8) south, range thirty-four (34) east Boise meridian; thence east one (1) mile to the northeast corner of section one (1), township nine (9) south, range thirty-four (34) east, Boise meridian; thence south two (2) miles to the southeast corner of section twelve (12); thence east two (2) miles to the northeast corner of section seventeen (17), township nine (9) south, range thirty-five (35) east, Boise meridian; thence south one and one-half (1 1/2) miles to the east quarter (E1/4) corner of section twenty (20); thence west one-half (1/2) mile to the center of section twenty (20); thence south two and one-half (2 1/2) miles to the south quarter (S1/4) corner of section thirty-two (32), township nine (9) south, range thirty-five (35) east, Boise meridian; thence east to the northeast corner of section five (5), township ten (10) south, range thirty-five (35) east, Boise meridian; thence south one and one-quarter (1 1/4) miles to the southeast corner of the northeast quarter (NE1/4) of the northeast quarter (NE1/4) of section eight (8); thence west one-quarter (1/4) mile; thence south one-quarter (1/4) mile; thence west one and one-quarter (1 1/4) miles; thence south three-quarters (3/4) of a mile; thence west one-quarter (1/4) mile to the southwest corner of lot one (1) of section eighteen (18), township ten (10) south, range thirty-five (35) east, Boise meridian; thence south on the range line three and three-quarter (3 3/4) miles to the southwest corner of township ten (10) south, range thirty-five (35) east, Boise meridian; thence east one and three-quarters (1 3/4) miles to the northwest corner of section four (4), township eleven (11) south, range thirty-five (35) east, Boise meridian; thence south one (1) mile to the northwest corner of section nine (9); thence east one-quarter (1/4) mile; thence south one-half (1/2) mile; thence east one-half (1/2) mile; thence south one-half (1/2) mile; thence east one-quarter (1/4) mile to the northwest corner of section fifteen (15); thence south one-half (1/2) mile to the west one-quarter (1/4) corner of section fifteen (15); thence east one (1) mile; thence south one-half (1/2) mile to the northwest corner of section twenty-three (23), township eleven (11) south, range thirty-five (35) east, Boise meridian; thence following the unbroken crest of the main mountain range to the southeast corner of section twenty-four (24), township eleven (11) south, range thirty-five (35) east, Boise meridian; thence southerly and easterly along the crest of the mountains between Malad and Marsh valleys to a point on the north and south center line of section thirty-three (33), township twelve (12) south, range thirty-six (36) east, Boise meridian; thence north to the center line of section twenty-eight (28), township twelve (12) south, range thirty-six (36) east, Boise meridian; thence east three and one-half (3 1/2) miles through the center of sections twenty-seven (27), twenty-six (26) and twenty-five (25) to the east quarter (E1/4) corner of section twenty-five (25), township twelve (12) south, range thirty-six (36) east, Boise meridian; thence south between ranges thirty-six (36) and thirty-seven (37) east, Boise meridian; to the top of the crest of the mountains between Malad and Marsh valleys; thence in an easterly and southerly direction on the crest of the mountains between Malad and Marsh valleys to a point on the Oxford mountain range where the same is intersected by the one-sixteenth (1/16) section line, eighty (80) rods, more or less, south of the township line between township thirteen (13) and fourteen (14) south.
Southern boundary. Thence east to the southeast corner of lot one (1), section four (4), township fourteen (14) south, range thirty-nine (39) east, Boise meridian; thence north six and one-quarter (6 1/4) miles to the northwest corner of section three (3), township thirteen (13) south, range thirty-nine (39) east, Boise meridian; thence east on township line sixteen and one-quarter (16 1/4) miles, more or less, to the summit of the Bear River range.
Eastern boundary. Thence north following the unbroken crest of the Bear River range to its intersection with the township line between townships nine (9) and ten (10) south; thence west on the township line to the southwest corner of section thirty-two (32), township nine (9) south, range forty-one (41) east, Boise meridian; thence north three (3) miles to the northwest corner of section twenty (20); thence west one (1) mile to the southwest corner of section eighteen (18), township nine (9) south, range forty-one (41) east, Boise meridian; thence north nine (9) miles to the northwest corner of section six (6), township eight (8) south, range forty-one (41) east, Boise meridian; thence west four (4) miles to the southwest corner of section thirty-three (33), township seven (7) south, range forty (40) east, Boise meridian; thence north six (6) miles to the northwest corner of section four (4), township seven (7) south, range forty (40) east, Boise meridian; thence west one and one-half (1 1/2) miles to the southwest corner of section thirty-one (31), township six (6) south, range forty (40) east, Boise meridian; thence north six (6) miles to the northwest corner of township six (6) south, range forty (40) east, Boise meridian; thence west six (6) miles to the southwest corner of township five (5) south, range thirty-nine (39) east, Boise meridian; thence north to the township line between townships four (4) and five (5) south.
Northern boundary. Thence west along said township line between townships four (4) and five (5) south to the place of beginning.
Idaho Code § 31-105