| Country: | VNM |
| Type: | QL |
| Route: | 1B |
| Length Km: | 135 |
| Direction A: | East |
| Terminus A: | in Dong Dang, Cao Loc |
| Junction: |
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| Direction B: | East |
| Terminus B: | intersection near the Gia Bay Bridge, Thái Nguyên |
| Previous Type: | QL |
| Previous Route: | 1 |
| Next Type: | QL |
| Next Route: | 1C |
National Route 1B is a 135 km long east-west Vietnamese highway. The starting point is in Dong Dang town, Cao Loc district, Lang Son province at the intersection of National highways 1 and 4A. The end of the route is at the crossroads near Gia Bay bridge in Thai Nguyen city. National Route 1B runs through the districts of Cao Loc, Van Quan, Binh Gia, Bac Son, Vo Nhai, and Dong Hy.[1]