Minn. Stat. § 463.02: GRANT, CONDEMNATION OR DEDICATION.

Such easement may be acquired by the council by purchase, by grant, or by condemnation. It may also be created by dedication by indicating such building line upon any plat hereafter recorded in the office of the county recorder of the county where the land lies; and the council shall have power to refuse to accept or approve plats of lands unless building lines are shown thereon.