Chief Justice Warren delivered the opinion of the Court.
Wesberry clearly established that the fundamental principle of representative government in this country is one of equal numbers of people, without regard to race, sex, economic status, or place of residence within a State. Our problem, then, is to ascertain, in the instant cases, whether there are any constitutionally cognizable principles which would justify departures from the basic standard of equality among voters in the apportionment of seats in state legislatures. A predominant consideration in determining whether a State's legislative apportionment scheme constitutes an invidious discrimination violative of rights asserted under the Equal Protection Clause is that the rights allegedly impaired are individual and personal in nature. Undoubtedly, the right of suffrage is a fundamental matter in a free and democratic society. Especially since the right to exercise the franchise in a free and unimpaired manner is preservative of other basic civil and political rights, any alleged infringement of the right of citizens to vote must be carefully and meticulously scrutinized....
Legislators represent people, not trees or acres. Legislators are elected by voters, not farms or cities or economic interests. As long as ours is a representative form of government, the right to elect legislators in a free and unimpaired fashion is a bedrock of our political system. It could hardly be gainsaid that a constitutional claim had been asserted by an allegation that certain otherwise qualified voters had been entirely prohibited from voting for members of their state legislature. And, if a State should provide that the votes of citizens in one part of the State should be given two times, or five times, or ten times the weight of votes of citizens in another part of the State, it could hardly be contended that the right to vote of those residing in the disfavored areas had not been effectively diluted. Of course, the effect of state legislative districting schemes which give the same number of representatives to unequal numbers of constituents is identical. Weighting the votes of citizens differently, by any method or means, merely because of where they happen to reside, hardly seems justifiable....
Logically, in a society ostensibly grounded on representative government, it would seem reasonable that a majority of the people of a State could elect a majority of that State's legislators. To sanction minority control of state legislative bodies would appear to deny majority rights in a way that far surpasses any possible denial or minority rights that might otherwise be thought to result. And the concept of equal protection has been traditionally viewed as requiring the uniform treatment of persons standing in the same relation to the governmental action questioned or challenged. With respect to the allocation of legislative representation, all voters, as citizens of a State, stand in the same relation regardless of where they live. Any suggested criteria for the differentiation of citizens are insufficient to justify any discrimination, as to the weight of their votes, unless relevant to the permissible purposes of legislative apportionment. Since the achieving of fair and effective representation for all citizens is concededly the basic aim of legislative apportionment, we conclude that the Equal Protection Clause guarantees the opportunity for equal participation by all voters in the election of state legislators. Diluting the weight of votes because of place of residence impairs basic constitutional rights under the Fourteenth Amendment just as much as invidious discriminations based upon factors such as race or economic status.... Our constitutional system amply provides for the protection of minorities by means other than giving them majority control of state legislatures.
We are told that the matter of apportioning representation in a state legislature is a complex and many-faceted one. We are advised that States can rationally consider factors other than populations. We are admonished not to restrict the power of the States to impose differing views as to political philosophy on their citizens. We are cautioned about the dangers of entering into political thickets and mathematical quagmires. Our answer is this: a denial of constitutionally protected rights demands judicial protection; our oath and our office require no less of us. To the extent that a citizen's right to vote is debased, he is that much less a citizen. The weight of a citizen's vote cannot be made to depend on where he lives. Population is, of necessity, the starting point for consideration and the controlling criterion for judgement in legislative apportionment controversies. A citizen, a qualified voter, is no more nor no less so because he lives in the city or on the farm. This is the clear and strong command of our Constitution's Equal Protection Clause. This is at the heart of Lincoln's vision of "government of the people, by the people,...for the people." We hold that, as a basic constitutional standard, the Equal Protection Clause requires that the seats in both houses of a bicameral state legislature must be apportioned on a population basis. Simply stated, an in-dividual's right to vote for state legislators is unconstitutionally impaired when its weight is in a substantial fashion diluted when compared with votes of citizens living in other parts of the state.