| 0 mile |
Begins within Billings as it branches off Interstate 90 to the north |
45°46′06.03″N, 108°29′60.00″W |
| 14 mile |
Passes by Acton |
45°55′54.10″N, 108°40′58.03″W |
| 29 mile |
Passes through Broadview |
46°05′39.12″N, 108°52′13.18″W |
| 43 mile |
At Lavina it turns west as it joins U.S. Route 12 |
46°18′22.73″N, 108°56′16.18″W |
| 46 mile |
Passes by Cushman |
46°18′21.76″N, 108°59′43.59″W |
| 58 mile |
Enters Ryegate where Highway 300 branches off to the south and Highway 238 branches off to the north |
46°17′49.45″N, 109°15′22.81″W |
| 61 mile |
Passes by Barber |
46°18′52.30″N, 109°23′01.36″W |
| 71 mile |
Passes by Shawmut |
46°20′41.71″N, 109°31′40.39″W |
| 87 mile |
East of Harlowton U.S. Route 12 continues west while Highway 3 joins U.S. Route 191 to the north |
46°26′09.18″N, 109°48′50.41″W |
| 106 mile |
Passes by Judith Gap |
46°40′43.67″N, 109°45′07.90″W |
| 111 mile |
Passes by Garneill |
46°45′02.37″N, 109°45′03.58″W |
| 127 mile |
Joins U.S. Route 87 and turns west where U.S. Route 191 ends while Highway 200 branches off to the east |
46°58′58.48″N, 109°44′42.56″W |
| 133 mile |
Highway 400 and Highway 239 branch off to the west at Hobson |
47°00′15.22″N, 109°52′10.82″W |
| 138 mile |
Passes by Moccasin where Highway 426 branches off to the north |
47°03′07.33″N, 109°54′14.51″W |
| 148 mile |
Passes by Windham where Highway 541 branches off to the south |
47°04′33.65″N, 110°08′36.93″W |
| 155 mile |
Enters Stanford where Highway 80 branches off to the north |
47°08′42.24″N, 110°13′19.56″W |
| 170 mile |
Passes by Geyser |
47°15′24.25″N, 110°29′48.50″W |
| 185 mile |
Passes by Raynesford where Highway 427 branches off to the south |
47°15′53.66″N, 110°43′26.07″W |
| 195 mile |
Joins U.S. Route 89 |
47°20′55.67″N, 110°53′46.48″W |
| 198 mile |
Passes by Belt |
47°22′18.64″N, 110°55′16.94″W |
| 205 mile |
Passes by Fife |
47°27′22.41″N, 111°04′24.21″W |
| 215 mile |
Ends at the outskirts of Great Falls |
47°29′33.89″N, 111°12′55.25″W |
