Mont. Code Ann. § 7-2-4301

Tracts or parcels of land proposed to be annexed to a city or town under the provisions of this part shall be deemed contiguous to such city or town even though such tracts or parcels of land may be separated from such city or town by a street or other roadway, irrigation ditch, drainage ditch, stream, river, or a strip of unplatted land too narrow or too small to be platted.