All items of tax levy of any district authorized by Sections 6-501, 6-503 and 6-504 of this Code shall be extended by the county clerk as one tax upon the collector’s book and, except as hereinafter provided in this Section, shall be paid to the treasurer of the district by the collector as fast as the same is collected, other than such rate per cent as shall be allowed for collecting the same.
     One half the tax required to be levied by Section 6-501 of this Code, on the property lying within a municipality in which the streets and alleys are under the care of the municipality shall be paid over to the treasurer of the municipality, to be appropriated to the improvement of roads or streets, either within or without the municipality and within the road district under the direction of the corporate authorities of the municipality. However, when any of the tax is expended beyond the limits of the municipality it shall be with the consent of the highway commissioner of the road district.
     If any municipality has not appropriated the taxes received by it as aforesaid for the improvement of roads or streets within one year from the date of the receipt thereof, then the unappropriated portion of such taxes shall forthwith be paid by the Treasurer of such municipality to the Treasurer of the road district from which such taxes were derived, to be used and expended for road purposes within such road district.