(a) General rule.--Within the year following that in which the Federal census, decennial or special, is officially and finally reported and at such other times as the governing body deems necessary, each entity having a governing body not entirely elected at large shall be reapportioned into districts by its governing body. The governing body shall number the districts.
(b) Composition of districts.--Districts shall be composed of compact and contiguous territory as nearly equal in population as practicable as officially and finally reported in the most recent Federal census, decennial or special.