The R175 is a regional road in County Louth linking the R173 at The Bush to the small port of Greenore on Carlingford Lough.
At the locality known as The Bush, the R173 – which has run some 14 km generally eastwards from its junction with the M1 immediately north of Dundalk – makes an unsignposted turn to the left to cross the site of the former railway station yard before taking up its subsequent more northerly course onwards to the border with Northern Ireland at County Bridge, southeast of Newry. From the motorist's perspective, the road from Dundalk flows seamslessly ahead to become the R175, the R173 / R175 together forming a high-quality link from the M1 to the port of Greenore.
Leaving the old station behind, the R175 procedes for the next 1.4 km as a high-standard S2, with hard shoulders, on the alignment of the former railway formation, thus avoiding several bends on the old L122. It then rejoins the general line of the original route at Grange. The next, 4-km-long, section to Greenore was also improved in the late 1960s, with some oxbow sections of the original road still in evidence. At 2.6 km from Grange there is a T-junction on the left with the R176 to Carlingford and Newry. After this, the R175 runs past the excellent golf course, towards the distinctive village and its privately owned port at the tip of the peninsula.
From the port, a ferry service operates across the narrow mouth of the lough to Greencastle.