Atlanta: The South's new-old city. The scene of next week's Democratic convention has been in a constant state of rebuilding and renewal since the Civil War. The result - a hustling city unlike any other in Dixie.

If Scarlett O'Hara lived today, she might be a realtor in suburban Gwinnett County, selling tract Taras to Northerners, and never looking back. The Atlanta that becomes the center of national attention next week during the Democratic National Convention is undeniably the gleaming, hustling, yuppie-laden, commercial capital of the Southeast.

And undeniably the city thrives partly through a major moral achievement. It made good on its boastful slogan - ``A city too busy to hate'' - through the tumult of the civil rights years, and is today arguably the nation's most hospitable city for the rising black middle class.

The rest of the South yearns only reluctantly for Atlanta-style prosperity. Other Southerners tend to see in Atlanta all the warm Southern charm and heritage of, say, Los Angeles.

``The South wants to have it both ways,'' says Charles Wilson, historian at the University of Mississippi's Center for the Study of Southern Culture. ``It wants to have the kind of boosterism that Atlanta has and retain its Southern charm.''

In the end, Dr. Wilson speculates, the South will choose to trade its roots for the traffic jams and white-collar jobs of Atlanta - whenever it gets the chance.

For comparisons with the modern Atlanta, observers look to Dallas, Denver, or Los Angeles.

Atlanta is something of a boomtown for service professionals. The Democratic convention will be only the fourth largest in the city this year. The airport handles more flights than any other in the nation.

The accents heard in Atlanta offices are as likely to be from Ohio or Pennsylvania as from Georgia. The scent of economic opportunity is in the air. Corporate climbers, here on tours of duty, typically want to stay.

Yet business in Atlanta retains something of a Southern style - despite the sarcastic label of ``California East.''

``In many ways, the old guard still greatly influences the style,'' says Alan Jenks, who lived in New York and London before coming to Atlanta and publishing an economic newsletter. Atlantans doing business take more time to get acquainted than do people in many other cities, he observes.

``You don't see that graciousness in New York or San Francisco,'' he says.

Atlanta proper has a higher share of poverty than any American city save Newark, N.J. But greater Atlanta is prosperous, well below the national average in unemployment and with nearly double the national rate of job growth.

Atlanta is an overwhelmingly new city continually under construction. When General Sherman burned the city on his march to the sea in 1864, he set a precedent followed by generations of developers. That tradition - out with the old, in with the new - only now is giving way to a growing movement to preserve historic buildings and neighborhoods. And only slightly.

``Atlanta has been in a boom stage since the Civil War,'' says Eileen Segrest, a leading preservationist - ``a perpetual Reconstruction.''

``Atlanta has always sort of looked over the horizon and said, `What next?''' says Dan Sweat, who until recently was director of Central Atlanta Progress. ``Frankly, I like that.''

Atlanta's emergence in the past three decades is ascribed to two things: building a huge airport ahead of its time and avoiding the brutal battles over civil rights that tarred other rising Southern cities.

Racial climate remains the most striking aspect of Atlanta. Black prosperity - like black poverty - is obvious everywhere.

The notion of a ``black Mecca'' is easy to exaggerate. Yet, says Owen Montague, president of a networking organization for black professionals, ``Here in Atlanta, I feel I have a better shot at the American dream than anywhere else.''

This is more obvious to people moving to Atlanta than to natives, he notes. ``In Northern cities,'' he says, ``covert racism has become a fine art. It hasn't become a fine art yet in Atlanta.''

Race is up front in Atlanta. ``More than most cities, Atlanta is racially aware,'' says Angelo Fuster, once and future press secretary to former Mayor Maynard Jackson. Atlantans are quite conscious of the racial mix of social or business groups, he says.

Blacks and whites in Atlanta seem to mingle more, less self-consciously, than in most other cities. One reason is the city's thriving black middle class, rooted in the city's elite, century-old black colleges.

Atlanta's current mayor, Andrew Young, is an acclaimed international booster for the city, but is sometimes suspected by blacks, especially poor blacks, of not being a strong enough advocate. (His day-to-day management of the city is almost universally criticized as what political columnist Bill Shipp calls ``amateur night at the water department.'')

Still, Atlanta is by no means integrated. While 25 percent of greater Atlanta is black, fully two-thirds of the city itself is black. The majority are poor and short of stable housing.

``I think Atlanta has lost its way,'' says Austin Ford, an Episcopal clergyman who runs a community center in a poor neighborhood. Atlanta has steadily destroyed low-income housing for 20 years and left the poor to make do. The city that reared Martin Luther King Jr. and built the nation's first public housing project ``has really been mean about this.''

Meanwhile, the middle class, black and white, moves to the suburbs. Says the Rev. Mr. Ford: ``Maybe they don't care, but they don't see.''

Mr. Sweat, spokesman for the downtown business leadership for the past two decades, says that Atlanta - nearly finished for the moment building road systems - is about to embark on a major plan to better human services such as education and housing.

``We shall see,'' says Ford.