Every statutory section-line highway shall be sixty-six feet wide and shall be taken equally from each side of the section line, unless changed as provided in this title, but nothing herein contained shall prevent the highway authority charged with the construction, reconstruction, or repair of any public highway along a section line from purchasing or condemning right-of-way for widening the highway to more than sixty-six feet or from purchasing or condemning more right-of-way on one side of the section line than on the other, provided they deem it necessary so to do in order to provide a better highway, to avoid destruction of trees or valuable buildings or to avoid unsuitable terrain.
SDCL 31-18-2