Reynolds v. Sims was a United States Supreme Court case with the verdict that the legislative districts across states must be equal in population, as stated in the Equal Protection Clause of the Fourteenth Amendment.
Prior to this ruling, many state legislative chambers had districts with an uneven number of population, Reynolds v. Sims happened in Alabama where the constitution allowed for one senator per county regardless of its population, this provision was opposed by voters.
Chief Justice Warren ruled that population must always be the 'controlling consideration' in state redistricting.
