In connection with the acquisition of property or property rights for any controlled-access facility or portion thereof, or service road in connection therewith, the state, county, city, or town highway authority may acquire an entire lot, block, or tract of land, if, by so doing, the interests of the public will be best served, even though the entire lot, block, or tract is not immediately needed for the right-of-way proper.
SDCL 31-8-8