The highway connects the northern part of the Thomson area to the South Carolina state line, via Lincolnton.

SR 43 beings at an intersection with US 78/SR 10/SR 17 (Washington Road) north of Thomson in McDuffie County.

It continues to the north-northeast, and intersects SR 220 in the southern portion of the county, just south-southwest of Loco.

[6][7] By the end of 1937, the segment of SR 70 from Lincolnton to the South Carolina state line had a "sand clay or top soil" surface.

[8][9] In 1938, a small portion of the highway southwest of Lincolnton had a "completed hard surface".

[3][11] Between 1946 and 1948, the segment from the southern terminus to a point southwest of Lincolnton had a "sand clay, top soil, or stabilized earth" surface.

[14][15] The next year, the segment from the southern terminus to the Little River crossing was hard surfaced.

It travels to the northwest and meets its northern terminus, an intersection with US 378/SR 43 northeast of the city, in a place known as Wright's Crossing.