The highway received its current designation after the Portage la Prairie bypass was completed and opened to traffic in 1970.

As noted in the Portage la Prairie section, this was the original route for PTH 1 through Brandon prior to 1959.

Large trucks travelling eastbound are not permitted to travel on the rural section of PTH 1A between Brandon and the Trans-Canada Highway near Kemnay due to a very low Canadian Pacific Railway bridge which passes over the highway just east of the small community; oversized trucks travelling westbound are rerouted on to a gravel road connecting PTH 1A and the Trans-Canada Highway less than 1 kilometre (0.62 mi) east of the underpass.

Despite the efforts of the Manitoba government to prevent oversized trucks from attempting to travel under this bridge (which include flashing overhead signs alerting overheight vehicles of the bridge and other signs directing these vehicles to either turn around and/or detour), there are still numerous incidents of trucks either crashing into the bridge or getting stuck in the opening, causing extended closures of the route.

[4][5][6] Eastbound traffic on the Trans-Canada Highway encounters a sign advising vehicles above the 3.7m limit requiring access to Brandon to continue traveling on PTH 1 approximately 2 kilometres (1.2 mi) before the junction.