All districts organized under authority of this article shall be special or local improvement districts. The assessments levied by, for, or on behalf of any such district shall be local or special improvement assessments. Such assessments shall be determined and levied according to the benefits to accrue to each tract of land included in any such district and not otherwise. No tract of land so included shall be burdened by cumulative levies or otherwise for the payment of delinquencies or defaults in the payment of assessments levied against other lands in such district.L. 23: p. 507, § 21. CSA: C. 138, § 37. CRS 53: § 149-5-21. C.R.S. 1963: § 150-4-21.