The Straight was constructed in the late 1830s and early 1840s. Earlier maps - Taylor and Skinner's Maps of the Roads of Ireland from 1776, the Cork Parliamentary Borough map of 1832 - show no track at all in this area. By the first edition of the Ordnance Survey map in 1841-42, work was in progress. Before construction the land was an osiery, a willow-fringed swamp with green fields stretching for miles. Local tradition holds that the road was a Famine Road, and the tradition is partly right. The Straight itself was built by 1842, before the Great Famine struck, but the section out as far as Leemount Cross - including the new bridge over the River Lee - may not have been completed until the famine years of 1845 to 1850, when destitute labour was deployed on public works to keep starvation at bay.

In the 1880s the Muskerry Tram came through. Twenty-one stations along the line, with one at the western end of the Straight at Carrigrohane and another at Leemount Cross, connected Cork city to Blarney, Coachford, and Donoughmore. The locals called it the Hook and Eye, and the joke was that passengers could pick blackberries from the moving carriages. Ticket collectors moved between carriages along the outside of the train while it was still in motion - a procedure described in surviving accounts as very dangerous because of the rocking and swaying. In 1926 one of the more unusual moments in the tram's history occurred when a tram collided with a steamroller in the middle of the Carrigrohane Straight. The steamroller was resurfacing the road. The tram derailed. A few passengers fainted. Nobody was hurt. The tram closed for good in December 1934.

The Straight was originally surfaced in limestone. In 1927 the County Council and Cork Corporation, who shared jurisdiction over different sections, laid reinforced concrete instead. The project was unusual enough that the Carrigrohane Straight became one of the first concrete road surfaces in either Ireland or Great Britain. The reinforced concrete sections were about 20 feet long and several inches thick, with bitumen expansion joints between them. Concrete was chosen for the boggy ground; the same logic produced concrete roads in Northern Ireland a few years later, including the Ballymena-to-Ballymoney route. The South of Ireland Asphalt Company hand-laid the concrete. After the tram tracks were removed in 1935 the recovered ten feet of width was also concreted, and that original concrete - on the section outside the city, on the south side of the road - is still there beneath later resurfacing.

By the 1920s and 1930s the combination of the Straight and the parallel Model Farm Road had become a perfect closed circuit, two long straights connected at each end - flat, fast, and ready-made. Cork organised motor races on it. Drivers came from across Europe, motorbikes including 750 cc Yamahas competed alongside Formula-style cars, and the 1938 Cork Grand Prix reportedly drew 70,000 spectators - a figure that is hard to picture today on a stretch of road that now carries commuter traffic and a flooding-prone car dealership district. Rosemary Smith's 1978 record run is the closest thing to a successor. In recent decades the Straight has continued to host speed trials and land speed record attempts, and it featured in the Cork 800 festivities marking the city's eighth centenary, including events called the Great Race and Steeple Jack.

The Straight is dead flat, which is why it is fast - and which is also why it floods. The Shournagh joins the Lee at Crubeen Bridge on the Lee Road. The smaller Carrig joins at the junction under Carrigrohane Castle, forded by what was once known as Cromwell's Bridge. With two tributaries pouring into the Lee at this point, the road takes water from both rivers in winter and from spring tides at the city end. The flood of 1916 was the worst, reaching Inichigaggin Lane at 28 feet above sea level. The flood of 1962 was tidal rather than fluvial, climbing 19 feet above sea level and submerging the city centre courthouse along with the road. The Inniscarra and Carrigadrohid hydroelectric dams upriver have eased the worst of it, but the Straight still floods. The cars still race when the weather holds. Both things, somehow, remain true.