Songwriter Johnny Mercer would be proud of his home town if he could see it now. Like many other natives in this century. Mercer left this proud birthplace of the state of Georgia to seek his fortune elsewhere. He never completely severed his tie with Savannah. He had family and friends here. And he drew on this romantic coastal city of the Old South for muscial inspiration until his death in 1976.

Other Savannah are coming home again, and those who never left are finding little reason to move away. All they might want in life they can find right here. While residents of other American cities continue their exodus to the suburbs, the suburbanities here are moving back into the city.

They are discovering the rejuvenated Savannah to be, as some visitors have called it, America's most livable city.

Life moves at a pleasant and relaxed pace in this balmy climate. But there is no doubt that the one-time big cotton exporting city is undergoing a Renaissance. It's in the air, and there is tangible evidence in the revival and restoration of formerly decaying neighborhoods and a general cleanup of the environment.

Two recent development point up the apparent rebirth of this historic city, which through its nearly 2 1/2 centuries of existence has had its economic ups and downs.

In June, a new riverfront plaza, lined with shops and restaurants, was ceremoniously dedicated. This $7-million project, funded through a combination of federal and local money, is expected to give the city a great economic and recreational boost.

The Historic Savannah Foundation, Inc., which has spearheaded restoration of the city's old neighborhoods, has announced that work has been completed on virtually all of the 18th-and early-19th-century houses deemed worthy of restoring in a comprehensive survey made in the 1950s, and found that about 1,100 of these had sufficient historic or architectural value to be worth saving. Audrey Rhangos, acting executive director of the foundation, reports that more than 1,000 of these now have been restored.

"We're not saying every one of these renovations was a major restoration," said Rhangos. "The scope varied greatly according to the individual structure.But whatever work was required to make these buildings livable once again now has been completed on nearly all that were listed."

General economic improvement in the area has seen the city's unemployment rate go down to 7.6 per cent. The city complete construction of a water pollution control center nearly two years ago and as a result is pollution in the Savannah River is no longer a problem. Local industry has been installing anti-air pollution devices. The Chamber of Commerce reports that lcal plants are meeting state air quality standards, which are tougher than federal standards. A giant pulp and paper mill on the river northwest of the city has spent a great amount of money to improve its air pollution control even though the prevailing winds are from the southeast.

Race relations here have shown marked improvement. Restoration of old residential areas has included homes for blacks as well as whites. The board of trustees of Historic Savannah Foundation numbers several blacks among its members, including City Councilman Roy Jackson.

The restoration movement and revival of the city center got under way in 1955, when a group of women, shocked by the demolition of Savannah's old Market House, decided, "That's enough." Their efforts were directed first at saving the Isaiah Davenport House, a fine Georgian period home on Columbia Square, which also was threatened by the wrecking ball. The building was preserved and opened to the public as a museum, and its basement became the headquarters for Historic Savannah.

Today, the headquarters is in the William Scarbrough House, built in 1818-19 by architect William Jay, of Bath, England, and regarded as one of America's finest surviving examples of Regency period architecture, Restoration of this mansion, acquired in rundown condition in 1972, was made a 1976 American Bicentennial project.

The reopening of Scarbrough House is in itself a fine augury for the future of the dilapidated west end of downtown. Nearby is a giant new civic center. In this rea, too, the Chamber of Commerce and Savannah Visitors Center occupy the old Central of Georgia Railroad Station. Restoration of this 1860 structure is a grand example of reconversion of an outmoded building.

After restoration of the Davenport House two decades ago, the Historic Savannah Foundation's plan for saving other old homes was evolved. With the initial help of a small group of businessmen and bankers, a revolving fund was instituted. This money has been used to purchase some old properties when they were put on the market and then sell the buildings and land to anyone who would promise to restore the structures inside and out.

Native sons who had made their mark elsewhere, began returning. Among the first was Mills B. Lane, who, in Atlanta, had become president of Georgia's largest bank. Lane moved into a restored home and began what he called "private urban renewal." He bought and restored a number of old houses, selling them to other middle-and upper-income families moving back into the city.

Lane also restored blocks of nowhouses occupied by poor blacks, renting them back to their occupants without a rent increase. Now retired, banker Lane remains a respected figure in the Savannah Renaissance.

What made saving center city Savannah worthwhile was the inspired scheme for the original 1733 settlement laid out by Gen. James Oglethorpe. As with William Penn. founder of Philadelphia a half century earlier. Oglethorpe came over from England with a blueprint for a planned city. The streets of his Savannah were to follow a grill pattern, with block-square parks at intervals.

Oglethorpe's plan laid the design for the original squares; the city elders through the years continued that plan, extending the number of squares to an eventual 24. Facing these green oases, grand townhouses were built. Twenty of these little parks have survived. Historic Savannah Foundation and others are continuing their work to save and restore the houses around them.

This park-townhouses pattern gives Savannah its individuality, its ambience and its air of gracious living. The green squares with their moss-draped live oaks and other trees and shrubbery provide a pause for motorists and drivers of commercial vehciles who must drive around them instead of roaring straight down the city streets.

Congestion is avoided by expediting motor traffic on several one-way through streets. As in other cities, downtown parking can be a problem, particularly since demolition of old buildings to make way for parking lots has been halted. However, numerous parking lots are permitted, provided they "camouflage" their property to blend in with their surroundings.

The squares and the variety of the buildings and monuments make Savannah a good walking town. Day or night, it is pleasant to walk here. In this way it is comparable to Charleston's Battery Park neighborhood, Philadelphia's 18th-century Society Hill section and London's Mayfair.

A good headquarters for an in-town stay is the DeSoto Hilton Hotel, which a decade ago replaced the old Victorian-style DeSoto Hotel, a Savannah landmark. The new DeSoto Hilton may have updated the facilities of its predecessor but it retrogressed in replacing the old hotel's full-sized swimming pool by an outdoor bathtub perhaps 10 yards in length.

If you don't mind commuting 10 miles or so for your outings in downtown Savannah, particularly if you are a swimmer, by all means stay at the Savannah Inn (the former Oglethorpe Hotel) and Country Club, along a waterway at Wilmington Island and near the ocean beach. This beatifully renovated hostelry of the 1920s has a championship golf course, tennis courts and a swimming pool some 40 yards in length.

Rambles around town should include such sights as the Bull Street parks known as the "Jewels of Savannah" and including Johnson Square, Wright Square, Chippewa Square (with its fine statue of Gen. Oglethorpe), Madison Square and Monterey Square.

Old buildings not to be missed include the Juliet Gordon Low Birthplace, owned by the Girl Scouts of America and dedicated as a memorial to their founder; the Green-Meldrim Home, headquarters of Union Gen. William T. Sherman at the end of the Civil War and now the Parish House for St. John's Episcopal Church; and Hodgson Hall, headquarters of the Georgia Hostorical Society.

The Historic Savannah Foundation conducts fine sightseeing tours but the chief delight in visiting Savannah comes in walking around town on your own. Around every corner you will find new delights - if old homes and restoration are your cup of tea.

For wining and dining, restoration of old buildings has scored more points. Everyone knows the Pirate's House, at the east end of town. A preserved seamen's tavern of the 18th century, it has 23 dining rooms. The Herb House, standing next door and dating from 1734, is regarded as Savannah's oldest building. The Trustees' Garden here was the first major restoration project, predating the Historic Savannah program by a few years.

On Reynolds Square is the Pink House, a restaurant reveling in the atmosphere of 1771, when the house was built. It was one of the few fine 18th-century buildings left standing after military action in the Revolutionary War and the great fires of 1796 and 1820. The Pink House in recent times has been joined by the "17 Hundred 90," another beautiful townhouse converted to a restaurant that has gained recognition for its fine food.

Just outside downtown Savannah is Thunderbolt, an old fishing village. At Tassey's Pier restaurant, the Geechee stew is a must.

The newly restored River Street section in Savannah features a number of new restaurants lining the riverfront plaza, and the "Ships of the Sea" museum, another benefactor Mills B. Lane project.

On the bluff above River Street is Factors' Row, once the center of the cotton trade. Now business offices are located in this area of the Savannah riverfront revival.

Opposite Factors' Row, on Bay Street, is the old Customs House, on the site of a building where Gen. Oglethorpe lived when he founded the colony of Georgia. Next door is the Mercer insurance agency office. The family is songwriter Johnny Mercer no longer is connected with it, but the name survives. To memorialize Mercer and his music, plans call for conversion of Savannah's old Lucas Theater, built in 1921, to the Johnny Mercer Theater Restaurant.

Although the Historic Savannah Foundation has achieved its original aim, preserving the surviving historic and architectural gems of the late 18th and early 19th centuries, its work continues. According to Audrey Rhangos, the organization now is turning its attention to preserving Victorian period homes and reviving old commercial buildings. And plans are under way for rebuilding that old Market House whose demolition touched off the restoration campaign two decades ago.

So far, restoration of old homes in Savannah has been good business. Some properties are said to have quadrupled in value since work was done on them. In the old historic section, properties a few years ago could be purchased for from $15,000 to $25,000 and restored for another $40,000. Inflation of the past three years has greatly added to these costs. It is estimated that as the program now moves into the Victorian neighborhoods the cost of restoration can run to $20,000 to $25,000 per floor.

Savannah's restoration to date has been accomplished almost entirely with private funds and private investment. As the program advances into the later Victorian areas, now housing moderate and low-income groups, it is anticipated that some form of government help may be needed to provide rental housing.

The rejuvenated Savannah has long since emerged from its cocoon.Its progress has been substantial. But there is still a way to go, and an opportunity for the visitor to this old city to observe the process - if no longer from a front row seat, at least from history's mezzanine.