Atlanta, now a busy hub, was once the end of the line

One day in 1837, the chief engineer of the Western & Atlantic Railroad told one of his crewmen to hammer a spike into the ground. Here's the spot, he probably said. Here is where the rail line should end. That's how the city of Atlanta got to be situated where it is.

People did not have great hopes for the little hamlet that had grown up by the time the first train actually arrived there. But in time it became the premier city in Georgia and indeed the hub of the Southeast.

The place was called Terminus at first, and eventually renamed Atlanta, a ''feminized'' version of ''Atlantic.'' The spot where the spike was driven has become Five Points, the heart of downtown Atlanta.

From the start, accessibility was the key to Atlanta's prosperity; Atlanta was less important for what it was than for being easy to get to. The importance of rail access has diminished, but that hub function is more important than ever. The engineer's spike nailed down a future for Atlanta of air passengers changing planes, of boxcars switching tracks, of checks clearing banks, of satellite transmissions relayed by microwave tower.

''I would almost make the analogy that the Southeastern region is a huge parabolic mirror of manufacturers, trade, consumption, and so on,'' says Sam Williams, manager of the Atlanta Market Center; ''and the focal point of that mirror is Atlanta.''

Atlanta seems to be a city that, like the well-known brand of cakes, nobody doesn't like. Nobody, that is, except Georgians outside Atlanta, who regard the metropolis as a mass of torn-up expressways - a perception not without a certain basis in fact.

Businesses, however, report that it's much easier to transfer people into Atlanta than back out. Housing is a relative bargain. And Atlanta retains something of the air of an overgrown smaller city.

''It's a big-league town, but still you know most of the folks in town,'' says John Imlay of the computer software firm Management Science America Inc. ''Organizations such as Kiwanis and Rotary are still pretty big. It's almost provincial from that standpoint.''

Metro Atlanta accounts for virtually half of the state. Places that used to be little towns out in the country have awakened and found themselves deputized into suburbia.

Atlantans claim proudly that their city has no natural barriers to keep it from spreading out to the horizon and beyond. They are right.

But the reverse of that coin is that geographical barriers can help define a city. With nothing to hinder people from building out and out and out, there is no incentive to maintain the urban core.

Ironically, centrifugal force seems in danger of tearing the hub city apart. In Atlanta, as in other cities, growth on the outskirts, including such places as the paradoxically named ''Perimeter Center,'' is seen sapping downtown and leading to mindless jumble.

Losing touch with its center could lead to another tear in Atlanta's social fabric: to the isolation of blacks and whites.

Dan Sweat, president of Central Atlanta Progress, a downtown development organization, says, ''We're creating two cities, one white, on the north side of town, and one black, on the south side.'' Technology firms, particularly, are setting up north of town.

Atlanta has long been the home of a solid black middle class, but it also has a large concentration of poor black people who left the farm heading for Detroit or New York but never made it past Atlanta.

Says Donald Stewart, president of Spelman College, part of the historically black Atlanta University Center, ''I suspect that there are some problems in terms of the interface or fit between where black people live and where the growth is, particularly in the high-tech companies. If these are largely high-tech industries, they will require skill levels that many blacks will not be able to reach. I think these are two places where the lines don't cross.''

In its attempts to make order out of urban chaos, Atlanta is hampered by its relative lack of a 19th-century ''village'' base to build upon. This owes partly to General Sherman's visit, and partly to the fact that the city grew up during the automobile age.

While proclaiming Atlanta ''a delightful city,'' Spelman's Dr. Stewart also calls it ''an amorphous mass with some nice neighborhoods.'' He adds, ''One doesn't feel Atlanta.''

He tells of having his first sightseeing tour of Atlanta. ''What this person did was to take us into a series of hotel lobbies. . . . I kept thinking, But where is the city?''

One hopeful sign is the progress in developing the new subway system, parts of which are already open and heavily used.

Architect John Portman says, ''The rapid transit system will have as profound an effect as the highway system did after World War II. The highway system, however, was primarily designed to take people out. Rapid transit is designed primarily to bring people in.''