SDCL § 31-4-222: State Highway 251 from Nebraska to U.S. Highway 18.

The state trunk highway system include the following in Gregory County:

From a point on the Nebraska state line south of Gregory near the southeast corner of section thirty-five, township ninety-five north, range seventy-three west, thence north to U.S. Highway 18 near the northeast corner of section fourteen, township ninety-seven north, range seventy-three west.