Idaho Code § 62-107
Any railroad corporation chartered by or organized under the laws of this state, or of any state or territory, or under the laws of the United States, and authorized to do business in this state, may extend its railroad from any point named in its charter or articles of incorporation, or may build branch roads, either from any point on its line of road or from any point on the line of any other railroad connecting, or to be connected, with its road, the use of which other road between such points and the connection with its own road, such corporation shall have secured by lease or agreement for a term of not less than ten (10) years from its date. Before making any such extension, or building any such branch road, such corporation shall, by resolution of its directors or trustees, to be entered in the record of its proceedings, designate the route of such proposed extension or branch by indicating the place from and to which said railroad is to be constructed, and the estimated length of such railroad, and the name of each county in this state through or into which it is constructed or intended to be constructed, and file a copy of such record, certified by the president and secretary, in the office of the secretary of state, who shall indorse thereon the date of filing thereof and record the same. Thereupon such corporation shall have all the rights and privileges to make such extension or build such branch, and receive aid thereto, which it would have had if it had been authorized in its charter or articles of incorporation.
Idaho Code § 62-107