WASHINGTON — If there's one thing the sharply divided nation can agree on after nearly eight years of President Barack Obama, it is that things have changed on his watch.
Most notably, his appearance.
Even the president has noticed. Opening his speech at the Democratic National Convention last week, Obama praised his wife Michelle, the 52-year-old first lady, who "somehow hasn't aged a day."
"I know the same cannot be said for me," Obama continued with a chuckle. Twelve years after a wunderkind 42-year-old Illinois state senator burst onto the national scene with a youthful vigor and forward-looking exuberance, the president's once-black hair has gone nearly fully gray. The creases around his mouth and under his eyes have grown deeper.
"My girls remind me all the time: 'Wow, you've changed so much, daddy,' " he said. "And then they try to clean it up. Not bad, just more mature."
On Thursday, the 44th president turns 55.
It's his final birthday in office, and it comes at a time when Obama is acknowledging that his own political shelf life is winding down. Though mid-50s is young for an outgoing commander-in-chief, and he will presumably enjoy a long, active post-presidency, Obama has grown increasingly wistful in his final year.
"It's true, I was so young that first time in Boston," he said last week, reflecting on the speech at the 2004 convention that helped launch his political rise.
At times on the world stage, Obama has taken on the tone of the wizened dad, or at least big brother, dispensing advice to a new generation of younger leaders.
"I had no gray hair when I was in your shoes seven years ago," Obama told Canada's boyish Prime Minister Justin Trudeau, then 43, during their first bilateral meeting last November. "You need to start dyeing it soon because it gets too late."
"So young — and yet so cynical," Trudeau interjected with a laugh. But the prime minister then revealed what Obama told him during a congratulatory phone call after Trudeau was elected.
"What Barack pointed out to me about how fast his daughters grew in the seven years since that first night of his electoral victory really struck home for me," Trudeau said.
In June, Obama declined an invitation to speak at older daughter Malia's graduation from Sidwell Friends School, for fear that he might tear up.
It has become something of a habit for the public to compare before and after shots of two-term presidents and to fret about how much the weight of responsibility for the nation's security and prosperity takes its toll on each occupant of the White House. That pastime has become accentuated in the social media age; Twitter users bandied about mockups of the 2004 Obama and the 2016 Obama during his convention speech last week.
For Obama, the gray hair is so obvious that it has become part of his stump speech, a way to disarm his audience by poking fun at himself. But by other measures, he has remained fit and vibrant.
Though he has hung up his basketball sneakers, Obama's morning gym workouts and frequent golf course outings, along with his famous personal discipline at the snack table, have left him not just leaner than he was two years ago — but also, incredibly, taller.
Obama checked in at 175 pounds and 6 feet 1½ inches on his most recent personal physical — five pounds less and a half-inch taller than in 2014, according to a medical report released by the White House in March.
Once a smoker, the president remains tobacco free and only drinks alcohol in moderation; his bad cholesterol is low and his good cholesterol is high, the exam found.
"All clinical data indicates that the President is currently very healthy and that he will remain so for the duration of his Presidency," his doctor, Ronny Jackson, concluded.
Obama has used past birthdays to have a date night with the first lady, raise money for his 2012 campaign and shoot hoops with professional basketball stars.
This year, though, the president has surrounded himself with friends from the good old days. Obama was joined on the golf course at Camp David last weekend by Chicago neighbor Martin Nesbitt, high school pals Mike Ramos and Bobby Titcomb, and college friends Laurent Delanney and Hasan Chandoo.
On Thursday, the president is scheduled to hold a private briefing with his national security team at the Pentagon, followed by a news conference, before departing on his annual two-week vacation to Martha's Vineyard on Friday. White House officials declined to say whether he was planning any birthday celebration.
Even if Obama is suddenly feeling more in touch with his mortality, he can take some solace that he will be replaced by someone a lot older — Hillary Clinton is 68 and Donald Trump is 70. But that seems of little comfort to a president who took office at 47 years old, the fifth-youngest to assume the White House.
At a forum with students in Kuala Lumpur last fall, Obama called on a young man who asked the president his advice as someone who "is aging to a very senior life."
"That's pretty low!" the president interjected.
Yes, the man said, but "what do you want to see from young people like us when you get old? You get my question."
"I got your question," Obama concurred. "Sit down. Well, the first thing I want from young people is to stop calling me old."