As human fingers are not equal, so also Settlements varied in size and population. The author tested the Zipf’s Rank Size Rule on settlements in Delta State. This is an attempt to apply the Zipf’s Rank Size Rule which states that, if the population size of settlements in a country (geographic entity) are arranged in a descending order and are ranked in that manner, that the population of a settlement ranked “n” will be 1/nth of the population of the largest settlement. This was applied to settlements in Delta State Nigeria, by arranging and ranking the population of the settlements in a descending order. In applying the Zipf’s Rule of dividing the population of the most populated settlement by the ranks of each settlements to derive the equivalent of the population of such settlements, it was discovered that only one settlement agreed to this rule. Other theories like Law of Primate City, Christaller’s Centre Place Theory, and others were also discussed and applied. To ascertain the pattern of the settlements distribution, the nearest neighbour index was extensively applied to the three senatorial districts of the state using well structured maps.