The “Solid South” was a political fact, benefiting Democrats for generations and then Republicans, with Bible Belt and racial politics ruling the day.

But demographic changes and recent election results reveal a more nuanced landscape now as the two major parties prepare for their national conventions. Republicans will convene Aug. 27 in Florida, well established as a melting-pot battleground state, to nominate Mitt Romney of Massachusetts. Democrats will toast President Barack Obama the following week in North Carolina, the perfect example of a Southern electorate not so easily pigeon-holed.

Obama won both states and Virginia four years ago, propelled by young voters, nonwhites and suburban independents. Virginia, long a two-party state in down-ballot races, had not sided with Democrats on the presidency since Lyndon Johnson in 1964. Jimmy Carter in 1976 had been the last Democratic nominee to win North Carolina. Each state is in play again, with Romney needing to reclaim Florida and at least one of the others to reach the White House.