The road starts at a junction with the A72 southeast of Hamilton and heads southeast straight through the town of Larkhall, leaving town along Carlisle Road. The road then meets the M74 at J8 (Canderside Toll), where it also crosses the A71.
We now run alongside the motorway for 3 miles before going over it to enter Kirkmuirhill. The road goes straight through the town and is the dominant number in a multiplex with the B7086. On the far side of town the lengthy sliproad from J9 meets us; this was once the D2A74 Kirkmuirhill bypass. A short distance further on we cross the motorway at J10 (Wellburn Interchange), which provides the three movements J9 doesn't. Here the B7078 turns into a dual carriageway and heads south between the motorway and Lesmahagow. After peeling away from the motorway the B7018 is met.
The road becomes S2 again for a few miles before returning to the M74 at J11 (Poniel Interchange), where we actually have to TOTSO right on meeting the northbound onslip. We continue south as a dual-carriageway road on the eastern side of the motorway and pass Happendon services (also known as Cairn Lodge), which is accessed via our road and (for southbound traffic) gaps in the central reservation. We then cross the Douglas Water to meet the A70 and the M74 at J12 (Millbank Interchange). There's a multiplex with the A-road through the junction and slightly beyond before our road turns left to regain its number.
We continue south, again as single-carriageway, although the road does show signs of having been D2, with the wide expanses of gravel left and a cycle lane occupying what was the northbound carriageway. We diverge from the motorway and meet the B740 from Crawfordjohn. After going over the Duneaton Water the road ends at (Abington Interchange), which is J13 of the M74 and A74(M), where we also meet the A702. That road continues south, with Abington half a mile ahead.
This road was formerly the A74. The northern end (Draffan to Larkhall) was superseded by the M74 in 1966 but was not downgraded until the early 1970s, whilst the section between Draffan and Uddington was downgraded in 1987 when the M74 was extended to the south. This section remains a dual carriageway through Lesmahagow and also between J11 and J12 of the M74. The southernmost section, Uddington to Abington (J12 - J13 of the M74), was downgraded in 1991 and was converted to a single carriageway and cycle track several years later.