One person, one vote

"One person, one vote" (also known as "one man, one vote") expresses the principle that individuals should have equal representation in voting. This slogan is used by advocates of political equality to refer to the concept that voters may not vote multiple times in an election, and to advocate for electoral reforms such as universal suffrage, combatting gerrymandering, eliminating the electoral collage, and to advocate for voting reforms which ensure an equally weighted vote, such as STAR voting and Approval voting.

The British trade unionist George Howell used the phrase "one man, one vote" in political pamphlets in 1880. During the 20th-century period of de-colonisation and the struggles for national sovereignty, from the late 1940s onwards, this phrase became widely used in developing countries where majority populations sought to gain political power in proportion to their numbers.[citation needed] The slogan was notably used by the anti-apartheid movement during the 1980s, which sought to end white minority rule in South Africa.

In the United States, the "one person, one vote" principle was invoked in a series of cases by the Warren Court in the 1960s, during the height of related civil rights activities. Applying the Equal Protection Clause of the United States Constitution, the Supreme Court majority opinion (5–4) led by Chief Justice Earl Warren in Reynolds v. Sims (1964) ruled that state legislatures, unlike the United States Congress, needed to have representation in both houses that was based on districts containing roughly equal populations, with redistricting as needed after censuses. Some had an upper house based on an equal number of representatives to be elected from each county, which gave undue political power to rural counties. Many states had neglected to redistrict for decades during the 20th century, even as population increased in urban, industrialized areas. In 1964, Wesberry v. Sanders, the U.S. Supreme Court declared that equality of voting - one person, one vote - means that "the weight and worth of the citizens' votes as nearly as is practicable must be the same." and ruled that states must also draw federal congressional districts containing roughly equal represented populations.

Court cases
In Colegrove v. Green, 328 U.S. 549 (1946) the United States Supreme Court held in a 4-3 plurality decision that Article I, Section 4 left to the legislature of each state the authority to establish the time, place, and manner of holding elections for representatives.

However, in Baker v. Carr, 369 U.S. 186 (1962) the United States Supreme Court under Chief Justice Earl Warren overturned the previous decision in Colegrove holding that malapportionment claims under the Equal Protection Clause of the Fourteenth Amendment were not exempt from judicial review under Article IV, Section 4, as the equal protection issue in this case was separate from any political questions. The "one person, one vote" doctrine, which requires electoral districts to be apportioned according to population, thus making each district roughly equal in population, was further affirmed by the Warren Court in the landmark cases that followed Baker, including Gray v. Sanders, 372 U.S. 368 (1963), which concerned the county unit system in Georgia; Reynolds v. Sims, 377 U.S. 533 (1964) which concerned state legislature districts; Wesberry v. Sanders, 376 U.S. 1 (1964), which concerned U.S. Congressional districts; and Avery v. Midland County, 390 U.S. 474 (1968) which concerned local government districts.

The Warren Court's decision was upheld in Board of Estimate of City of New York v. Morris, 489 U.S. 688 (1989). Evenwel v. Abbott, 578 U.S. ___ (2016), said states may use total population in drawing districts.