| Province: | SK |
| Type: | Hwy |
| Route: | 18 |
| Photo Notes: | Highway 18 at dawn in winter |
| Photo Width: | 250 |
| Length Km: | 711.9 |
| Length Round: | 1 |
| Direction A: | West |
| Terminus A: | near Robsart |
| Junction: | |
| Direction B: | East |
| Terminus B: | at Manitoba border near Gainsborough |
| Rural Municipalities: | Reno, Frontier, Lone Tree, Val Marie, Glen McPherson, Mankota, Waverley, Old Post, Poplar Valley, Hart Butte, Happy Valley, Surprise Valley, Lake Alma, Cambria, Estevan, Coalfields, Enniskillen, Mount Pleasant, Argyle |
| Previous Type: | Hwy |
| Previous Route: | 17 |
| Next Type: | Hwy |
| Next Route: | 19 |
Highway 18 is a provincial highway in the Canadian province of Saskatchewan. It runs from Highway 13 near Robsart, approximately east of the Alberta border, to the Manitoba border near Gainsborough, where it becomes Highway 3. It passes through three major communities, all in the eastern quarter of Saskatchewan – Estevan, Oxbow, and Carnduff; it also passes north of the west and east blocks of Grasslands National Park. Highway 18 is about long, which is the longest east-west highway and second longest highway in Saskatchewan.
The original segment of Highway 18 ran from the Manitoba border, through Estevan, to Lake Alma, before turning north, passing through Radville, and terminating at Highway 13 approximately 30km (20miles) west of Weyburn.[1] In the 1960s, Highway 18 was extended west to Highway 6 near Minton along an upgraded grid road, resulting in the north-south section between Lake Alma and Highway 13 being renumbered as Highway 28.[2] In the 1970s, Highway 18 was again extended west along a series of upgraded country roads and existing highways – former highways include Highway 336 between Coronach and Rockglen; Highway 319 between Wood Mountain and Highway 19 near Mankota; and Highway 46 between Highway 4 near Orkney and Claydon.[2] [3]
From west to east:[4]