"Size rather than number of voters is the criterion used in establishing district size. The difference in size between the largest and smallest districts from the ideal district, where all districts have the same population, is a source of contention. In 182 when Providence changed from 13 to 15 wards, there was a deviation of 10.6 percent between wards, deemed acceptable by the courts because, the judge ruled, the US Supreme Court has said 1.9 percent is acceptable. In the recent Johnston case, the total deviation came to 52.7 percent--a figure much too high to accept."
Smolski, Chester, "Voting Districts can be a Bone of Contention" (1990). Smolski Texts. 186.