# South Dakota Highway 42

South Dakota Highway 42 (SD 42) is a segmented state highway in southeastern South Dakota, United States. The first segment is a six-mile-long (9.7 km) highway in Aurora County. The second and longest is 60 miles (97 km) long and connects Ethan and Sioux Falls. The final segment connects Sioux Falls to Iowa Highway 9 southeast of Rowena.

## Route description

The westernmost segment of SD 42 begins at a junction with U.S. Route 281 (US 281) and travels east through open farmland. This is the shortest of the three segments; it is only about six miles (9.7 km) long, and it ends as the roadway crosses from Aurora County into Davison County.
The central segment of the highway begins at an intersection with SD 37 in rural Davison County. It heads east and crosses the BNSF Railway. Just east of the railroad, the route passes through the town of Ethan, then enters Hanson County. About six miles (9.7 km) farther east, SD 42 bends slightly to the south and crosses the James River. The highway continues east through the flat prairie and enters McCook County.
About five miles (8.0 km) east of the county line, the highway enters the city of Bridgewater. Here, it curves to the northeast and crosses another branch of the BNSF Railway before meeting the eastern terminus of SD 262. SD 42 then curves back to the east and leaves Bridgewater. It continues through flat farmland, intersecting US 81 and passing over the west fork of the Vermillion River. The route heads east about ten miles (16 km) before crossing the east fork of the Vermillion River, and then entering Minnehaha County.
In Minnehaha County, SD 42 intersects SD 19, and the two highways run east for about one mile (1.6 km) before SD 19 splits off to the north, and SD 42 continues east toward Sioux Falls. It intersects the northern terminus of SD 17 approximately three miles (4.8 km) west of the city. The central segment of SD 42 ends at Ellis Road near the Sioux Falls city limits.
The easternmost segment of SD 42 begins at Six Mile Road east of the city of Sioux Falls. It runs southeast, concurrent with SD 11 along Arrowhead Parkway. The two highways pass by a golf course and a park before crossing the Big Sioux River. East of the river, SD 11 turns to the north toward Brandon, and SD 42 curves to the east. The highway passes through the unincorporated community of Rowena before curving due south and crossing the Iowa state line. The route continues into Iowa as Iowa Highway 9.

## Major intersections

| County | Location | mi | km | Destinations | Notes |
| Aurora | ​ | 0.000 | 0.000 | US 281 (388th Avenue) – Stickney | Road continues as 265th Street |
| Aurora–Davison county line | ​ | 5.870 | 9.447 | 394th Avenue | Eastern end of state maintenance; road continues as 265th Street |
| Gap in route ||||||
| Davison | Ethan | 5.870 | 9.447 | SD 37 (410th Avenue) – Parkston, Mitchell | Western end of state maintenance; SDDOT signs this as western terminus; road continues as 265th Street |
| Hanson | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions |
| McCook | Bridgewater | 31.811 | 51.195 | SD 262 west – Bridgewater | |
| McCook | ​ | 37.100 | 59.707 | US 81 (441st Avenue) – I-90, Freeman, Salem | |
| Minnehaha | ​ | 51.089 | 82.220 | SD 19 south (455th Avenue) – Parker | Western end of SD 19 concurrency |
| Minnehaha | ​ | 52.102 | 83.850 | SD 19 north (456th Avenue) – Humboldt | Eastern end of SD 19 concurrency |
| Minnehaha | ​ | 62.101 | 99.942 | SD 17 south (466th Avenue) – Lennox | |
| Minnehaha | ​ | 65.101 | 104.770 | CR 139 (Ellis Road) – Ellis, Tea | Eastern end of state maintenance; road continues as 12th Street |
| Gap in route ||||||
| Minnehaha | ​ | 65.101 | 104.770 | CR 119 (Six Mile Road) | Western end of state maintenance; road continues as Arrowhead Parkway |
| Minnehaha | ​ | 67.334 | 108.364 | SD 11 north (481st Avenue) – Brandon | Eastern end of SD 11 concurrency |
| Minnehaha | ​ | 71.973 | 115.829 | Iowa 9 east / CR A10 | Iowa state line; road continues as Iowa 9 |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus ||||||