The president pulled his wife close and they danced a slow, dignified two-step while, offstage, Beyonce sang. The president spun first lady Michelle Obama once in a half-turn.
Obama cut loose in a faster groove a few minutes later, as Shakira, Mary J. Blige, Faith Hill and Mariah Carey sang along with Stevie Wonder to his "Sign, Sealed, Delivered." The song was played at nearly all of Obama's rallies throughout the campaign.
"You could tell that's a black president from the way he was moving," comedian Jamie Foxx joked following the dance.
The president wore white tie, while Michelle shimmered in a white, one-shouldered, floor-length gown. It was embellished from top to bottom with white floral details and made by 26-year-old New York designer Jason Wu.
"First of all, how good looking is my wife?" Obama asked the crowd of celebrities and supporters.
At the Obama Home States ball, the president pulled the first lady much closer than he did on their first dance. At one point, he wrapped both arms around her waist and locked his fingers together at the small of her back.
"Hello, everybody. Aloha. What's going on?" Obama said in the dialects of the Hawaii and Illinois contingents, saying they reflected his roots. "So many of you got involved not just in our campaign but in our lives."
At the Commander in Chief Ball, Obama and Vice President Joe Biden each saluted the nation's military men and women via satellite. Biden said he wasn't looking forward to his moment in the spotlight - the dancing, that is.
"The thing that frightens me the most (is) I'm going to have to stand in that circle and dance in a minute." At that, he laughed and did a quick sign of the cross.
The Obamas were more enthusiastic, splitting up to dance with Marine Sgt. Elidio Guillen of Madera, Calif. - who was shorter than dance partner Michelle - and Army Sgt. Margaret H. Herrera, who cried in the president's arms.
Despite the formal attire and celebrity entertainment, balls aren't overly fancy affairs. Lines often are long to get in, go to the bathroom or check your coat, and the food is heavy on vegetables with dip and cheese cubes.
In a sign, perhaps, of the tough economic times, guests who already paid anywhere from $75 for a ticket to thousands more for a package deal had to buy their own drinks served in small plastic cups. Beer went for $6, cocktails for $9 and champagne for $12.
People were standing in line outside Union Station to get into the Eastern States Ball an hour and a half after it started. Because of very limited seating at the Western ball, a number of attendees in long gowns and fancy dress plopped cross-legged on the floor.
"This is what happens in a down economy. No chairs, no highboys - it's the floor and plastic cups," commented ballgoer Brig Lawson, 38, of Las Vegas.
Director Ron Howard said he sympathized with the long day Obama was having.
"I feel bad for him," Howard said in an interview with The Associated Press at the Western Ball. "He's had a long day and now he has to do seven dances. This has got to be the grueling part for the first family."
At the Obama Home States ball, the dance floor was dominated by two little girls who skipped and twirled in matching red dresses while the grown-ups stood still, crowded around the stage waiting for Obama to appear.
Singer Sheryl Crow, doing a sound check for a performance later at the Midwestern Ball, said she was homesick.
"I have not seen my child in four days. I'm miserable," she told her band between songs.
But she was greeted by a cheering crowd later for her appropriate hit, "A Change Would Do You Good." When hip-hop star Wyclef Jean asked the men at the Mid-Atlantic Ball to pull off their tuxedo jackets and swing them in the air to show their support for Barack Obama, thousands did.
Jean played a raucous 30-minute set for the 7,000 guests, starting with an ad-lib ode to Obama: "With a father from Africa, with the spirit of America, we voted for him. Obama's the president."
At the Youth Ball, Kid Rock belted out songs as well-dresed 20-somethings mingled about. One of them walked up to a bartender, gave him a high five and said, "Barack Obama is president!"
Though the mood was celebratory, the reality that the country remains at war hung over the festivities at the Commander in Chief ball and a separate Heroes Red White & Blue Ball.
"Please know that you are in our thoughts and prayers today, every day, forever," Obama told troops at the Commander in Chief ball. "Tonight, we celebrate. Tomorrow, the work begins. ... Together, I am confident we will write the next great chapter in America's story."