Before the Civil War the United States Constitution did not provide specific protections for voting. Qualifications for voting were matters which neither the Constitution nor federal laws governed. At that time, although a few northern states permitted a small number of free black men to register and vote, slavery and restrictive state laws and practices led the franchise to be exercised almost exclusively by white males.
Shortly after the end of the Civil War Congress enacted the Military Reconstruction Act of 1867, which allowed former Confederate States to be readmitted to the Union if they adopted new state constitutions that permitted universal male suffrage. The 14th Amendment, which conferred citizenship to all persons born or naturalized in the United States, was ratified in 1868.
In 1870 the 15th Amendment was ratified, which provided specifically that the right to vote shall not be denied or abridged on the basis of race, color or previous condition of servitude. This superseded state laws that had directly prohibited black voting. Congress then enacted the Enforcement Act of 1870, which contained criminal penalties for interference with the right to vote, and the Force Act of 1871, which provided for federal election oversight.
As a result, in the former Confederate States, where new black citizens in some cases comprised outright or near majorities of the eligible voting population, hundreds of thousands -- perhaps one million -- recently-freed slaves registered to vote. Black candidates began for the first time to be elected to state, local and federal offices and to play a meaningful role in their governments.
The extension of the franchise to black citizens was strongly resisted. Among others, the Ku Klux Klan, the Knights of the White Camellia, and other terrorist organizations attempted to prevent the 15th Amendment from being enforced by violence and intimidation. Two decisions in 1876 by the Supreme Court narrowed the scope of enforcement under the Enforcement Act and the Force Act, and, together with the end of Reconstruction marked by the removal of federal troops after the Hayes-Tilden Compromise of 1877, resulted in a climate in which violence could be used to depress black voter turnout and fraud could be used to undo the effect of lawfully cast votes.
Once whites regained control of the state legislatures using these tactics, a process known as "Redemption," they used gerrymandering of election districts to further reduce black voting strength and minimize the number of black elected officials. In the 1890s, these states began to amend their constitutions and to enact a series of laws intended to re-establish and entrench white political supremacy.
Such disfranchising laws included poll taxes, literacy tests, vouchers of "good character," and disqualification for "crimes of moral turpitude." These laws were "color-blind" on their face, but were designed to exclude black citizens disproportionately by allowing white election officials to apply the procedures selectively. Other laws and practices, such as the "white primary,", attempted to evade the 15th Amendment by allowing "private" political parties to conduct elections and establish qualifications for their members.
As a result of these efforts, in the former Confederate states nearly all black citizens were disenfranchised and removed from by 1910. The process of restoring the rights taken stolen by these tactics would take many decades.
In Guinn v. United States, 238 U.S. 347 (1915), the Supreme Court held that voter registration requirements containing "grandfather clauses,", which made voter registration in part dependent upon whether the applicant was descended from men enfranchised before enactment of the 15th Amendment violated that amendment. The Supreme Court found the Oklahoma law was adopted in order to give whites, who might otherwise have been disfranchised by the state's literacy test, a way of qualifying to vote that was not available to blacks. In 1944, the Supreme Court held that the Texas "white primary" violated the 15th Amendment. Smith v. Allwright, 321 U.S. 649 (1944). The Southern states experimented with numerous additional restrictions to limit black participation in politics, many of which were struck down by federal courts over the next decade.
Congress passed legislation in 1957, 1960, and 1964 that contained voting-related provisions. The 1957 Act created the Civil Rights Division within the Department of Justice and the Commission on Civil Rights; the Attorney General was given authority to intervene in and institute lawsuits seeking injunctive relief against violations of the 15th Amendment. The 1960 Act permitted federal courts to appoint voting referees to conduct voter registration following a judicial finding of voting discrimination. The 1964 Act also contained several relatively minor voting-related provisions. Although court decisions and these laws made it more difficult, at least in theory, for states to keep all of their black citizens disenfranchised, the strategy of litigation on a case-by-case basis proved to be of very limited success in the jurisdictions were sued and it did not prompt voluntary compliance among jurisdictions that had not been sued. Literacy tests, poll taxes, and other formal and informal practices combined to keep black registration rates minimal in Alabama, Louisiana, and Mississippi, and well below white registration rates in the others.
Faced with the prospect that black voter registration could not be suppressed forever, however, some states began to change political boundaries and election structures so as to minimize the impact of black re-enfranchisement. In 1960, the Supreme Court struck down one such effort, in which the state legislature had gerrymandered the city boundaries of Tuskegee, Alabama, so as to remove all but a handful of the city's black registered voters. The Supreme Court ruled that by doing so Alabama had violated the 15th Amendment. Gomillion v. Lightfoot, 364 U.S. 339 (1960).
In the early 1960s, the Supreme Court also overcame its reluctance to apply the Constitution to unfair redistricting practices. Prior to 1962, the United States Supreme Court had declined to decide constitutional challenges to legislative apportionment schemes, on the grounds that such "political questions" were not within the federal courts' jurisdiction. In Baker v. Carr, 369 U.S. 186 (1962), however, the Supreme Court recognized that grossly malapportioned state legislative districts could seriously undervalue -- or dilute -- the voting strength of the residents of overpopulated districts while overvaluing the voting strength of residents of underpopulated districts. The Supreme Court found that such malapportionment could be challenged in federal court under the Equal Protection Clause of the 14th Amendment.
In later cases including Gray v. Sanders, 372 U.S. 368 (1963), Reynolds v. Sims, 377 U.S. 533 (1964), and Wesberry v. Sanders, 376 U.S. 1 (1964), the Supreme Court established the one-person, one-vote principle. Because in many states malapportioned legislative districts had resulted in sparsely-populated rural counties having a much greater share of their state's political power than their state's population, correcting this imbalance led to dramatic realignments of political power in several states. In Fortson v. Dorsey, 379 U.S. 433 (1965), the Supreme Court suggested, but did not hold, that certain types of apportionment might unconstitutionally dilute the voting strength of racial minorities.