| I-15 | |||
| Get started | Monida Pass | ||
| End | sweetgrass | ||
| Length | 398 mi | ||
| Length | 640 km | ||
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Interstate 15 or I -15 is an Interstate Highway in the U.S. state of Montana. The highway forms a north-south route in the west of the state, and is the only north-south route in the sparsely populated state to be developed as a highway. The highway begins at Monida Pass at the Idaho border, and passes through a number of small towns to the Canadian border at Sweetgrass, before continuing as Alberta Highway 4 toward Calgary. The route in Montana is partly mountainous, and partly crosses the High Plains. The route is 640 kilometers long.
- 800ZipCodes: Provides a list of all postal codes in the state of Montana, covering area code, zip code and map for each city within Montana.
Travel directions
I-15 at Butte.
I-15 at Great Falls.
At the 2,094-foot-tall Monida Pass, Interstate 15 in Idaho merges into Montana. The highway runs north through the Red Rock River valley. On both sides of the highway are mountains that reach up to 3200 meters. This area is very sparsely populated, with sporadic turnings into remote hamlets. The first place you come across is Dillon, after 100 kilometers. Further north, one again crosses the Continental Divide, the watershed between the two oceans at 1799 meters, Deer Lodge Pass. Not far after this, I-15 joins Interstate 90, just west of Butte. Northwest, I-90 leads to Missoula, Spokane, and finally Seattle. I-90 and I-15 are double-numbered here near the mining town of Butte, which has 34,000 inhabitants, and is the largest town for miles around. To the center of Butte, Interstate 115 exits, a short highway that is more of a long exit. On the east side of town, I-15 turns north and continues eastwards I-90 to Billings, and on across the vast prairies.
- a2zDirectory: Lists popular attractions in Montana, including parks, festivals and holidays of Montana.
North of Butte you pass the Elk Grant Pass, which is 1941 meters high. After this, I-15 descends quickly toward Helena, the state capital of Montana. Here one crosses the US 12, which runs west to I-90 and Missoula, and east to Miles City in eastern Montana. Helena itself is small, with 26,000 inhabitants. People come here more on the plateau of the High Plains. At Holter Dam, US 287 turns north, including Glacier National Park. From here, the highway also parallels the Missouri River. Not far from the highway are high mountain ranges such as the Big Belt Mountains and the Little Belt Mountains, which reach up to 2800 meters. After this, you pass Great Falls, with 57,000 inhabitants the largest city on the route, and the second largest city in the state. The highway runs west of the city. A little further on, the US 89 turns off, which leads to Glacier National Park. This area consists mainly of agricultural areas. Winter driving can be dangerous here during snow storms, due to the remoteness of this area. The agricultural areas are occasionally interrupted by wild hills. The last slightly larger town before the Canadian border is Shelby, where theUS 2 crosses the northernmost US Highway. From here one can go to Kalispell to the west, and Glasgow to the east. Due to the total lack of commuter traffic, the highway is very quiet. At Sweetgrass one crosses the Canadian border, after which the road continues as Highway 4 in Alberta, a 2×2 divided highway. From here you can travel on to Lethbridge, Calgary and Edmonton.
History
The predecessor of I-15 was US 91, large parts of I-15 have been built directly over US 91, so that the original route has mostly disappeared, or only fulfills a local importance in places where I-15 does not directly cross the old route. route could be constructed.
I-15 was largely put into service in the 1960s and early 1970s. Construction of the Monida Pass section was awarded in 1958, Montana’s first Interstate Highway to be built. The first stretch of double-lane road opened in 1960 between Cascade and Ulm, a stretch more than 20 kilometers southwest of Great Falls. Fragmented sections opened up in Montana in the first half of the 1960s, with the first longer continuous stretch around the capital Helena, where a 42-kilometer stretch was open from 1964. In 1971 the route was continuous between Helena and Great Falls. By the mid-1970s the route was largely complete, the last two missing links being along Dillon in southern Montana and the twisty section between Butte and Boulder. The section along Dillon opened in the late 1970s or early 1980s, the mountain section between Butte and Boulder only followed around 1987 and was completed much later than the rest of I-15 in Montana. The section south of Dillon opened in 1988, the last stretch of Interstate Highway to be opened in Montana. As a result, I-15 was both the first and last section of the Interstate Highways built in Montana.
Opening history
The years are an indication and derived from the official state highway maps.
| from | nasty | length | date |
| Exit 256 Cascade | Exit 270 Ulm | 23 km | 1960 |
| Exit 358 Shelby | Exit 364 Shelby | 10 km | 1961 |
| Exit 282 Great Falls | Exit 290 Vaughn | 13 km | 1961 |
| Exit 389 Sunburst | Exit 394 | 8 km | 1963 |
| Exit 254 Cascade | Exit 256 Cascade | 3 km | 1963 |
| Exit 0 Idaho state line | Exit 15 Lima | 24 km | 1963 |
| Exit 119 Silver Bow | Exit 121 I-90 (west) | 2 km | 1963 |
| Exit 190 Helena | Exit 216 | 42 km | 1964 |
| Exit 328 Brady | Exit 335 Conrad | 11 km | 1964 |
| Exit 364 Shelby | Exit 379 Oilmont | 24 km | 1965 |
| Exit 394 | Exit 397 Canadian border | 5 km | 1965 |
| Exit 216 | Exit 228 US 287 | 19 km | 1966 |
| Exit 277 Great Falls | Exit 282 Great Falls | 8 km | 1967 |
| Exit 228 US 287 | Exit 234 Craig | 10 km | 1968 |
| Exit 250 | Exit 254 Cascade | 6 km | 1968 |
| Exit 182 Clancy | Exit 190 Helena | 13 km | 1969 |
| Exit 129 I-90 (East) | Exit 134 | 8 km | 1969 |
| Exit 37 Red Rock | Exit 52 Dalys | 24 km | 1969 |
| Exit 270 Ulm | Exit 277 Great Falls | 11 km | 1970 |
| Exit 15 Lima | Exit 37 Red Rock | 35 km | 1971 |
| Exit 234 Craig | Exit 250 | 26 km | 1971 |
| Exit 379 Oilmont | Exit 389 Sunburst | 16 km | 1971 |
| Exit 63 Dillon | Exit 93 Melrose | 48 km | 1973 |
| Exit 164 Boulder | Exit 182 Clancy | 29 km | 1973 |
| Exit 290 Vaughn | Exit 302 Power | 19 km | 1973 |
| Exit 335 Conrad | Exit 352 | 27 km | 1974 |
| Exit 302 Power | Exit 313 Dutton | 18 km | 1975 |
| Exit 111 | Exit 119 Silver Bow | 13 km | 1975 |
| Exit 93 Melrose | Exit 111 | 29 km | 1976 |
| Exit 313 Dutton | Exit 328 Brady | 24 km | 1977 |
| Exit 134 | Exit 138 Elk Park | 6 km | 1977 |
| Exit 352 | Exit 358 Shelby | 10 km | 1978 |
| Exit 138 Elk Park | Exit 164 Boulder | 42 km | 1987 |
| Exit 52 Dalys | Exit 63 Dillon | 18 km | 1988 |
Traffic intensities
The traffic volumes on I-15 are very low almost everywhere. More than 5,000 vehicles per day travel on only a small number of routes. The busiest point is the double numbering with I-90 at Butte where 19,000 vehicles run per day. In the capital Helena there are a maximum of 12,000 vehicles and in Great Falls just 10,000 vehicles are tapped per day. Only 2,000 vehicles per day drive on the border with Canada.
Lane Configuration
| From | Unpleasant | Lanes | Comments |
| exit 0 | Exit 398 | 2×2 |
