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.