Quarterbridge takes its name from the medieval Manx system of dividing land into quarterlands. The bridge marks the boundary between two of them, Ballabrooie and Ballaquayle. In the old order, a quarterland included a kerroo or farmstead, and four such quarterlands made up a treen. Land rights for the treen were entrusted to a landholder, who farmed one quarterland and rented the other three to freemen. Those freemen paid in cash, in produce and in services to the parish, including the upkeep of a small church or keeill within the treen. The Gaelic name, Droichead an Cheathru, means simply "bridge of the quarter." It is a name layered like the stones beneath it, every stratum recording a different age of the island's life.

The 1727 storm took out the first bridge. The replacement two-arched span was strung up downstream as a hurried fix, and that lasted until Charles Scott built the present alignment in 1809. The Union Hotel that stood at the junction burned down in 1830 and was rebuilt as the Quarterbridge Hotel. In 1873 a gatehouse and rail crossing appeared, part of the Isle of Man Railway's new Douglas-to-Peel line. Each generation widened the road a little more: a major project in 1937 demolished the Brown Bobby public house; the winter of 1953-54 reshaped the approach for the 1954 TT; a roundabout arrived in 1963; mini-roundabouts replaced it in winter 1986-87, taking out an old traffic island and a stand of cherry trees. The most recent overhaul came in early 2011, when the Department of Infrastructure resurfaced and re-drained the junction and shifted the pedestrian barriers beside the hotel.

From late May into early June, Quarterbridge stops being a road junction and becomes a stage. Motorcycles take this right-hander roughly a mile from the TT Grandstand, the first proper braking point on the 37.7-mile Snaefell Mountain Course. The corner has been part of the course since 1911, the year the Mountain Course was introduced for the Tourist Trophy races, and from 1923 it has also carried the Manx Grand Prix. But Quarterbridge's racing pedigree runs deeper. From 1904 to 1922 the junction served the Highland Course and Four Inch Course for car races including the Gordon Bennett Trial and the RAC Tourist Trophy. The start line for the original Highland Course was right here, at the meeting with the A5 New Castletown Road. The 1905 International Motorcycle Cup Races used Quarterbridge as both start and finish.

Standing inside the corner, the Quarterbridge Hotel has long been one of the most popular spectator points on the course, its outdoor terrace filling up on race days with fans who can hear the engines from a mile away. Yet the building itself has been part of the conversation about safety. In July 2008 the Department of Transport announced a four-million-pound road safety scheme for the junction that proposed demolishing the hotel and replacing the layout with a new roundabout. That particular scheme did not happen as proposed, and the hotel still stands, but the Quarterbridge keeps being adjusted bit by bit, every modification a quiet negotiation between an eighteenth-century crossing and twenty-first-century traffic. For one week each year, the negotiation is paused and the racers take the line.