The Deep South was, quite literally, a black and white world in 1965, when Congress approved the Voting Rights Act, sweeping away barriers that kept African-Americans from the polls.

And the Supreme Court decision on Tuesday, which struck down a key part of the law, is certain to set off a series of skirmishes over voting regulations between the white Republicans who control Southern state legislatures and civil rights groups seeking to maximize black voter clout.

But those who have studied the region closely say that a more unstoppable force is approaching that will alter the power structure throughout the South and upend the understanding of politics there: demographic change.

The states with the highest growth in the Latino population over the last decade are in the South, which is also absorbing an influx of people of all races moving in from other parts of the country.

While most experts expect battles over voting restrictions in the coming years, they say that ultimately those efforts cannot hold back the wave of change that will bring about a multiethnic South.

"All the voter suppression measures in the world aren’t going to be enough to eventually stem this rising tide," said Rep. David E. Price, a veteran North Carolina Democrat and a political scientist by training.

As the region continues to change, Republicans who control legislatures in the South will confront a basic question: how to retain political power when the demographics are no longer on your side.

The temptation in the short term, now that the Supreme Court has significantly relaxed federal oversight, may be to pass laws and gerrymander districts to protect Republican political power and limit the influence of the new more diverse population.

But that could be devastating to the party’s long-term prospects, especially if it is seen as discriminating against the groups that will make up an ever larger share of the future electorate.

The law guaranteeing political equality for blacks was passed nearly a half-century ago, in the wake of the startling images of violence in Selma, Ala. The nationally televised coverage shook America’s conscience and marked what President Lyndon B. Johnson would say in a speech to Congress was a moment where "history and fate meet at a single time in a single place to shape a turning point in man’s unending search for freedom."

The act eventually imposed federal oversight over nine states and other jurisdictions — among them, Alabama, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia — requiring them to seek preapproval for election laws, like voter identification measures, redistricting maps and rules related to the mechanics of elections, like polling hours.

The Supreme Court on Tuesday essentially struck down those preapproval requirements, which had deterred states and localities from passing legislation that they knew would meet with resistance from civil rights advocates and result in protracted fights.

Alabama, for example, passed a law in 2011 requiring that voters show photo identification at the polls. The state put off submitting the legislation to the Department of Justice, however — a delay some Democrats attribute to the state’s Republicans waiting for the Supreme Court decision.

But the most meaningful impact of the ruling may be seen in the decade to come, when Southern states — freed from federal preclearance requirements — take up the redrawing of congressional and legislative seats amid much more complex racial politics than in the days of Jim Crow.

As the white share of the population shrinks, Republican leaders are going to grapple with the same problem their Democratic counterparts faced as whites drifted from their ancestral party in the 1980s and 1990s.

"The South is going to start looking more like California eventually," said Arturo Vargas, executive director of the National Association of Latino Elected and Appointed Officials.

For years, black and white legislators in the South have agreed to district lines that, thanks to racial packing, create safe seats for both black Democrats and white Republicans. The Obama administration’s Department of Justice approved nearly every Southern redistricting map, written by Republicans, after the 2010 census.

The one exception, Texas, offers a window into what the future may look like in a multiracial South. With almost 90 percent of its growth owing to a mix of new Hispanic, Asian and black voters, Republican legislators in Texas drew new districts in 2011 that were rejected by a federal court as discriminatory because they didn’t sufficiently recognize the political power of the new demographics.

Just as Texas is now, Georgia will, thanks to polyglot Atlanta, eventually become a state where it will be difficult for Republicans to produce a redistricting map that protects their majority in perpetuity without drawing legal challenges.

Georgia’s Hispanic population nearly doubled between 2000 and 2010, according to federal census data. In suburban Atlanta’s Gwinnett County, the most heavily Hispanic locality in the state, the Latino population rose to 162,035 from 64,137.

"The growing nonwhite share of the electorate in Georgia and other Southern states represents a threat to the continued domination of the current majority party, which means that it is in the political interest of the majority party to do whatever it can, whether through control of redistricting or through the enactment of restrictive voter ID laws, to limit the impact of these trends," said Alan I. Abramowitz, an Emory University political scientist.

State Rep. Stacey Abrams of Georgia, the Democratic leader, said such efforts would trigger a backlash.

They’re going to be tempted to try to take advantage of this, but they risk permanently alienating a population that will eventually be able to take its revenge," Abrams said. "Given how quickly our Asian and Latino populations are growing and how much of the electorate they’re going to represent, to constrain their voting power would be a recipe for disaster."

Abrams’ Republican counterpart, the House speaker David Ralston, said the Voting Rights Act decision was an affirmation that his native region "has changed, has matured," and that his party would demonstrate that by appealing to Georgia’s changing face.

"If we’re going to govern responsibly and lead," Ralston said, "then we have to recognize that Georgia is a big state, it’s a diverse state, and it’s a state that’s changing."