When CBS broadcasts its $1 million Inaugural Eve concert Wednesday to an audience expected to number more than 50 million, television and President-elect Jimmy Carter will be carrying on a tradition that began with Franklin D. Roosevelt's third inaugural in 1941: the production of a big-name variety show to kick off a presidential term.

Although concerts and balls have been an inaugural feature since George Washington's time, the idea for a flashy, broadly-based event in Washington originally came from Carter T. Barron. Barron was the Georgia football player and Loew's Theater executive who became known as the show business ambassador to Washington, and whose name lives on in the 16th Street Amphitheater.

It was a time when theater managers played a conspicuous civic role in the community, planning benefits, fund-raisers and special balls. And Barrons's as plums on the inaugural bill pleased his corporate bosses.

It especially pleased, FDR, who thought it sounded "gala." So Gala became the name of Roosevelt's pre-inaugural evening.

Since then, each administration has tried its hand at a "festival," as they came to be called, and the events - by setting a tone of earthiness, elan, or confusion - sometimes have had an eerie way of foreshadowing an administration's future.

In 1941, the U.S. population was 131,669,275. Washington was a comparatively small Southern town where everyone seemed to know just about everyone else, and there was growing alarm about the 17-month-old war in Europe.

What the Roosevelt Inaugural III "Gala" had, above all, was class. It was in Constitution Hall, seating 3,800, and the line-up was pure cream. Little WINX (later WTOP) broadcast some of it, though radio was in the midst of the ASCAP-BMI battle of copyright holdings.

Playwright Robert E. Sherwood, who had become one of FDR's writers, was to have been emcee. When illness forced him out, dashing, adored Douglas Fairbanks Jr. took over in his British Navy uniform. Raymond Massey, who recently had scored as Sherwood's Lincoln, read from that play. At Mrs. Roosevelt's urging, the black Golden Gate Quartet appeared on the stage the DAR had denied Marian Anderson. That, like the third term itself, made another Roosevelt first. Mickey Rooney, the 19-year-old box office king, brought a piano concerto he'd composed for the occasion, then unleashed impressions of Clark Gable and Lionel Barrymore.

Jeanette MacDonald reminded Barron that she was a True Republican, so Nelson Eddy's singing partner was the Metropolitan Opera's Rise Stevens. Irving Berlin piped up with his "God Bless American," a relatively new song at the time. Ethel Barrymore, thinking of her one-time suitor Winston Churchill, read from Walt Whitman: "Liberty, let others despair of you. I never despair."

The highlight was Charlie Chaplin doing his mad monologue and dance from "The Great Dictator" to an violently anti-Hitler. In the middle of it, Chaplin lost his voice, asked for a glass of water, gulped, and resumed his Hitler to even greater effect. Singing the Truman Theme

Chairman of the Truman Gala of Jan. 19, 1949, was Melvin D. Hildreth, who assigned Carter Barron to command festivities accenting three individualistic Truman themes. It began with "Whistle Stop Express," with singer Gene Archer on a miniature train running around the Armory. Seven pianos with 14 pianists and girl singers for "I Love Piano," and Dorothy Mayor followed, the black soprano soaring with "Were You There When They Crucified My Lord?"

The night reflected Truman's down-to-earth affections: Lionel Hampton's band, Gene Kelley's softshoe dance, the teams of Abbott and Costello, Lum and Abner, and Joan Davis with composer Jule Styne as her accompanist. Lucy Monroedid what she did everywhere for 30 years: She sang "The Star-Spangled Banner."

Barron's committee included not only the gala-experienced Frances Nash, Perle Mesta and Jack Foxe, but also names still much with us: NBC's Bryson Rash, metro's Cody Pfanstiehl, the Redskin's Joel Margolis, the musicians union's Sam Jack Kaufman, Ray Bell, Sid Zins, David Pollard, Gerald G. Wagner, Dan Terrell, the Board of Trade's Clarence Arata, the Shoreham's Barnee Breeskin and Frank LaFalce. Working for Truman were such Californians as George Murphy and Ronald Reagan, later Republican senator and governor, respectively.

Tickets were $2.50, $7.50 and $10, and the show was supposed to run 2 1/2 hours. It ran 90 minutes over, thanks largely to stage-hogging by George Jessel, who's still at it. The tone suggested the democratic yeastiness of Truman's earned term. John Wayne for Ike

By the first Eisenhower-Nixon "Gala" of 1953, the U.S. population had grown to 150,697,381 and the capital was losing its small-town air. Demand for tickets was so strong that the Capitol was added to Uline's Arena, for a total of 9,000 seats. By then George Murphy was a Republican and the show's producer, with Radio City's Leon Leonidoff assisting him.

Logistics were immensely complex. Each of 25 acts had to be ferried, with motorcycle escort, between Uline's and the press Building - orchestrations included, Emcee John Wayne introduced, of all things, George Balanchine and his New York City Ballet stars: Hayden, Tallchief, Eglevsky, LeClerc and Magallenes. There were opera's Jan Peerce and Jarmila Novotna, TV's Sid Caesar and Imogene Coca, musical comedy's Ethel Merman and Bert Lahr, who did his "Woodman, Spare That Tree" classic. Unis stood on his finger; Abbott and Costello, apolitical, were back. Hoagy Carmicheal played "Stardust," and Lionel Hampton's band returned. In the galaxy of emcees for each act were Irene Dunne, Esther Williams, Walter Winchell and Ed Sullivan (who lost his voice). Irving Berlin's "I Like Ike" was a theme which lasted eight years.

Murphy also produced Eisenhower-Nixon II in the same locations, and while the second didn't have the panache of the first, it marked Pearl Bailey's first time at such a national clambake. She sang "Bill Bailey." Lou Costello was ill so Bud Abbott begged off, but Phil Silvers was on hand.

But the Uline-Capitol festivals had wider repercussions. First, became cleared than ever that a suitable hall and stage were vitally needed for what people were calling "The Capital of the Western World." In 1953, the Nixons, always punctual at public events, chatted of how such a place must be created. By 1957 "The Auditorium Committee," headed by Mrs. Eugene Meyer, had made progress on Capitol Hill. That year after years of public hearings, Congress passed the Fulbright-Thompson legislation for Foggy Bottom land to become what eventually was named the John. F. Kennedy Center for the Performing Arts. Urged on by Nixon, Ike signed the bill. Snowflakes in Camelot

JFK's Gala was for the books. It fell on the night of a snowfall which resulted in two deaths and 10,000 abandoned automobiles. Sir Laurence Olivier spent five hours getting from Alban Towers, where he was quartered, to the Armony. Ethel Merman couldn't get to the gown she'd planned for "Everything's Coming Up Roses." She was playing "Gypsy" in New York but, David Merrick closed it and his "Beckket" yo allow its stars, Olivier and Anthony Quinn, to be on producer Frank Sinatra's inaugural bill. The Gala set the tone for the Kennedy's Camelot years.

Their cohorts included Jimmy Durante, Mahalia Jackson, Milton Berle, Helen Trubel; such Rat Packers as Tony Curtis, Peter Lawford and Joey Bishop; Nat King Cole, Juliet Prowse, Ella Fitzgerald, Louis Prima, Fredric March, Keely Smith, Harry Belafonte and Leonard Berstein. The U.S. population had risen to 179,323,175 and everyone wanted to see the Beautiful People. You got Armory tickets by donating $100 to the Democratic National Committee.

When Sinatra arrived Jan. 5 on the Caroline, the Kennedy family's plane, the star was uninterested in locals who knew the area logistics. He brought in his own Hollywood gang, took over the tenth floor of the Statler and set up his own security forces. A Secret Service man told me, "Only Jack Kennedy can walk down this corridor uninvited." JOHNSON: Y'all Come

The Johnson-Humphrey "Gala of '65 was a "y'all come" free affair for 10,000 at the Armory, where producer Richard Adler previously had created two "Presidenticals" as JFK fund-raisers: One for the Democratic Party, and one for the Foggy Bottom arts center.

The LBJ Gala had the top current favorites: Fonteyn and Nureyev, Carol Channing and Carol Burnett, Julie Andrews, Barbra Streisand, Woddy Allen, Mike Nicholas and Elaine May, Ann-Margaret, Alfred Hitchcock, Bobby Darvin, Johnny Carson, Harry Belafonte and Mexico's Ballet Folklorico. The evening reflected the Johnson landslide. The quality of the stars set the tone of the LBJ White House after-dinner entertainments, first class all the way and Texas expansive. Sinatra for Nixon

Both Nixon-Agnew galas proved hectic. Ed McMahon produced the one in 1969, and Armory rehearsals weren't over until just before the 9 p.m. starting time. Seats were not in place. The $10 section was oversold, and holders of $1,000 boxes stalked angrily away after finding squatters in their seats.

Neither the President-elect nor Mrs. Nixon was there, but Mamie Eisenhower set a record as a White House intimate approached only by Eleanor Roosevelt and Dolley Madison. Julie, David and Tricia also represented the family.

Ailing Johnny Carson had to cancel out as emcee. The highlight was Joel Gray and the cast of "George M," which the Nixons had seen just after the election and invited to perform.

There was a return to the service academy choruses and bands, which had been subtly underplayed while Ike was President. Hugh O-Brien had moved ambitiously from the Johnson camp to the Nixon banner, Opera's Jan Peerce returned, as did Lionel Hampton Roger Williams sang "Autumn Leaves," as he would again four years later. Dinah Shore and Buddy Ebsen were there for TV, and Frank Lovell represented the astronauts.

For Nixon-Agnew II, the abiquitous Secret Service turned the Kennedy Center into a fortress. Double-parking by diplomats' chaufeurs outside the building jammed traffic to a standstill. It seemed that all the United States' 209,711.859 citizens wanted in.

There were four major events - a "Salute to the States" on Thursday, Jan. 18, and three more on Inauguration Eve: a "Youth Concert" in the Eisenhower Theater, "American Music" in the Opera House and the Philadelphia Orchestra in the Concert Hall.

Having unexpectedly sung "Fly Me to the Moon" on the 18th, Frank Sinatra decided he didn't have to show up for the announces Opera House date the next night. Sammy Davis Jr. had withdrawn from the "American Music" program and James Brown did the same from the Youth Concert. At the Opera House, Bob Hope found himself forced off stage by the Secret Service's split-second timing, cutting off his mike and turning out his lights and forcing Hope to yield to Vicki Caar. Offstage, Hope blew his stack.

What stories will emerge from the Center entertainments this week? The Inaugural Eve concert Wednesday promises Chevy Chase "satirizing Carter to his face," and a list of other entertainers that runs the gamut from Lily Tomlin to Johnny Cash. Countless other events have been planned. There are now 245,740,900 Americans, 85 million more than in FDR's 1941, and with television in on the act, more people than ever before are waiting to find out.