Within the year following that in which the Federal decennial census is officially reported as required by Federal law, and at such other times as the governing body of any municipality shall deem necessary, each municipality having a governing body not entirely elected at large shall be reapportioned, by its governing body or as shall otherwise be provided by uniform law, into districts which shall be composed of compact and contiguous territory as nearly equal in population as practicable, for the purpose of describing the districts for those not elected at large.