After a plank road shall have been acquired and taken possession of by a board or boards of chosen freeholders it may be widened to any width not exceeding one hundred feet, provided the board or boards of chosen freeholders of the county or counties in which such road may be situate shall adopt a resolution determining that such widening is of public importance and setting forth the width proposed, the location of the widening, and the points between which such widening is to be made. If the road lies in two or more counties the resolution shall receive the approval of each county before it becomes operative.