On Election Night, Sharon Pratt Dixon promised Washington "the best party this city has ever seen."

If the rest of her election promises live up to this one, the city has good reason to party. Last night's black-tie inaugural ball at Union Station was a high-spirited, strut-your-stuff affair with hot music, cool women -- and fireworks to boot.

The inaugural committee members transformed all of the gilded halls into one palatial ballroom for their Cinderella: Red roses in every urn, twinkling lights in every corner and a champagne flute for every hand.

Balls traditionally include dancing -- unless of course everyone's already cheek to cheek.

"In this situation," Dixon told the crowd packed in front of the main stage, "you got to either love each other or hate each other. I hope you're loving each other."

The audience responded with a resounding cheer.

The two major mysteries of the night were answered at the VIP reception at the Columbus Club before the gala:

1. What would the new mayor wear for her formal debut?

2. And who was that tall, dashing chap attached to her?

Answers:

1. Red and black. Specifically, her trademark scarlet, in rayon crepe with black silk taffeta shirred waist and sleeves, created by her favorite designer, daughter Aimee.

2. James R. Kelly III, a New York businessman. Specifically, owner of a telephone company and partial owner of WKYS-FM in Washington.

And the verdict for both?

"Fabulous!"

"Great!"

"Spectacular!"

First Glimpses

More than 6,000 people attended the gala, which cost $500,000 and was fully funded by ticket sales. General admission was $50 and senior citizens were admitted for $25. Box seats cost $1,500 to $10,000 and sky boxes, which held 48 people overlooking the grand hall of Union Station, went for a mere $50,000 each.

But hey, it only happens once every 12 ... er, four years.

The crowd got its first glimpse of the mayor at the VIP reception, where she was inundated by well-wishers and fans as strolling violinists played "This Could Be the Start of Something Big."

"She remembered me!" blurted out Evelyn Y. Davis, who was dressed in a full-length white fur coat. "She remembered me from the stockholders meeting at Pepco!"

"It was worth coming," gushed Gretchen Underwood of Boston.

"You know," interrupted her friend, Ronnie Lytle, pulling out from her purse a snapshot of the two with Dixon, "we gave Sharon a party on the Vineyard a year ago. We wanted everyone to meet Sharon Dixon."

"We knew she was going to win," said Underwood as Lytle held her camera in one hand and grabbed Dixon with the other for yet another shot for the scrapbook.

After two laps around the reception room -- each taking 30 minutes in the crush -- Dixon and her daughters were swept off to a holding room until 10 o'clock, when they were officially introduced -- but made no remarks -- to the gala audience.

She expertly waved her gloved hand and wore the biggest smile Washington has seen -- since Election Day.

The Family Hour

There were scads of Dixon relations at the VIP reception -- mostly women -- and they arrived in one explosion of red.

There was the tall, slender Drew, Dixon's glamorous younger daughter, with a Rob Lowe look-alike as her escort: Matthew McGuire, a 21-year-old anthropology student at Brown.

"She asked me a few weeks back," said McGuire. "And I couldn't turn it down. It's a once-in-a-lifetime thing."

Then there was Drew's sister Aimee, also in a red gown she designed. And the mayor's baby sister, Benaree "Bennie" Pratt Wiley of Boston.

"I'm so proud of her," Bennie beamed, "I can't really put it into words." And there were assorted cousins, nieces and others too numerous to mention -- all in some shade of Dixon Red.

Celebrating the Common Folk

"She's starting out with a huge bang," said Rep. Ron Dellums (D-Calif.). "And she has great support from the grass roots."

Unlike her swearing-in ceremony earlier in the day, which was filled with high-profile pols, last night's affair was a celebration for the common folk: business types, government workers and campaign volunteers.

A few celebrities sent congratulatory telegrams, which were read to the audience: Dionne Warwick ("Go, girl, go!"), Elizabeth Taylor, Roberta Flack, Bella Abzug, Barbara Jordan, Helen Reddy ("You are woman and they will hear your voice!") and hometown girl Shirley MacLaine ("I am with you in spirit").

Up in the sky boxes, purchased by corporations the likes of Shearson Lehman Hutton, Woodward & Lothrop and the Haft Co., the nattily attired nobility sipped champagne and nibbled chocolate truffles as they leaned over the granite railing to survey the scene below.

Everywhere they looked, there was music.

Enter Stage Right

The gala organizers set out to please all the people all the time by setting up four stages: Melba Moore and the Duke Ellington Orchestra on the first stage; local performers including the Duke Ellington High School Choir and the Gay Men's Chorus on Stage 2; Latin and reggae on the third; and -- are we hip or what? -- rap star Big Daddy Kane and go-go from local band Rare Essence on the fourth.

Not that there was any room to dance -- until the magic strains of the electric slide filled the hall. Suddenly, a mass of middle-age party animals flooded the floor in front of the main stage. The group, including Eleanor Holmes Norton, Washington's delegate-elect, broke into a world-record-size version of the line dance. And all through the rest of the train station, pickup groups followed their lead.

Except the new mayor. She was too bushed to boogie.