History of King's Highway 48B:
King's Highway 48B was created in 1966, when Highway 48 was relocated onto a new route which bypassed Beaverton entirely. Unlike many other Ontario Business Loops, Highway 48B was not created through a simple renumbering of the old Highway 48 alignment through Beaverton. In fact, a significant portion of the Highway 48B Business Loop actually followed the original route of Highway 12. Highway 48B began where the new Highway 48 Bypass joined the old route of Highway 12 south of Beaverton. From this point, Highway 48B ran northerly where it joined the original alignment of Highway 48 northeast of Port Bolster. From there, Highway 48B turned onto Lake Ridge Road (Old Highway 12 & Highway 48) and went through Downtown Beaverton along Osborne Street, Simcoe Street and Mara Road. Highway 48B ended several kilometres north of Beaverton, where the Beaverton Business Loop joined the Highway 12 & Highway 48 Bypass. The Highway 48B Business Loop survived until the late 1970s, when the entire route was decommissioned. Highway 48B was transferred to the Regional Municipality of Durham and the Township of Brock on July 12, 1978. Most of Highway 48B is now known as Durham Road 23. However, the north-south section that had initially been a part of the old Highway 12 alignment approaching Beaverton from Sunderland was renamed Side Road 17.