How old is too old to be president?
As Americans gear up to vote in this year's presidential election, it's a question that's been on a lot of people's minds.
Especially as the two oldest candidates to ever run for office in the US are running again — breaking the record for the oldest two people to ever compete for the presidency that they set four years ago.
Opinion polling has routinely found that voters don't like this, with more people worried about Joe Biden's age than Donald Trump's.
A February Ipsos poll found 59 per cent of voters thought both candidates were too old.
[Datawrapper: voter concerns]A New York Times/Siena poll found nearly half of voters thought Biden was too old to handle the job of president. If successful, Biden would be 82 years old at the start of his second term, four years older than Trump, who would be 78.
These concerns were amplified in the wake of Friday's presidential debate, during which Biden appeared frail, spoke quietly and seemed to lose his train of thought.
But here's the thing: Biden and Trump are not the only older politicians in Washington DC.
In fact, the average age in the US Congress has been climbing for decades and the current Congress is one of the oldest in history.
[Datawrapper: Median age of Congress]In the early 1980s, the median age of Congress was under 50, but it has been climbing steadily since then to just under 60 today.
Politicians are even older in the Senate, where politicians serve longer terms.
Around one in five members of Congress are aged 70 or over, but if you look at just the Senate, that rises to about a third of members.
The vicious cycle of alienation
Virtually all parliaments around the world are older than the population they represent. You'd expect that: we want people with life and work experience to be making important decisions, and older people tend to have more of that.
But the flip side is that many life experiences end up under-represented.
For instance, you end up with senior citizens interrogating Silicon Valley moguls about technology platforms that they clearly don't use.
"In general, representative democracy should try to represent their population," says Associate Professor Daniel Bessner from the University of Washington.
Joe Vogel is a delegate in Maryland's state parliament, the House of Delegates, and says America has changed dramatically since many lawmakers were young.
"We were having these conversations about what mass shooting drills are like in our schools," he says.
"I grew up in a generation where you would sit in a classroom and think of where your hiding spot was or whether you'd have time to run out the door. That is a perspective on these issues that a lot of my colleagues just don't have.
"Many of my colleagues had never lived at a time, had never gone to school at a time when those mass shootings were as common as they are now."'
Professor Daniel Stockemer from the University of Ottawa says a lack of youth representation makes a difference in how parliaments work and what is on the agenda.
"Young people don't participate that much … one of the reasons is that they are alienated," he says.
The theory goes that when young people don't participate in elections, they end up less represented in parliament, and that means they become dissatisfied and disinterested in politics.
"We call this the vicious cycle of political alienation," Stockemer says. "If a group is not at the decision-making table, it has very few possibilities to influence policies.
"Just think about gun laws in the US: even young Republicans favour stricter gun laws, young Democrats even more so.
"Older people [in] both parties are more hesitant, and so this is one of the signs that politics is really dominated by older people."
The US is the outlier
Stockemer, along with his colleagues, wanted to know more about how many young people were being elected to parliaments around the world.
Thousands of hours of work collecting biographical details of parliamentarians led to the creation of the Worldwide Age Representation in Parliaments dataset.
He says one thing stood out: "The US is rather the outlier."
Europe has some of the youngest parliaments in the world. The United Kingdom, with a median age of 50 in the House of Commons, appears roughly in the middle of the list of countries with relatively complete data.
Australia's parliament is a bit older, but the US is in a different league.
[Datawrapper: oldest parliament]The United States' outlier status is even more stark when you look at how things have changed over time for the oldest age groups.
To look at the over-representation of age groups, Stockemer calculated an "age representation index" to compare a group's share of parliament with their share of the population.
It shows that people aged 61 or over have rapidly become very over-represented.
[Data wrapper The United States is a global outlier in its representation of older people in parliament] Most countries are seeing more stability, or where older people are becoming over-represented, it's happening far more slowly.
"But … even stable is no progress," Stockemer says. "If you look at women or minorities ... even if we are far away from parity, we see progress.
"We've seen progress over the past years and decades. For young people, we've seen no progress. If at all, we've seen regression."
The single biggest contributor to the aging Congress is the aging population. As America has grown older since the baby boom, so have its politicians.
[Data wrapper: Congress has aged with the population]It really stands out now, though. Congress has for a long time been about 20 years older than the rest of the country, and that age gap now means a large share of politicians are over the retirement age.
Congresswoman Anna Paulina Luna says she can see that age gap in practice.
"For example, some people talk about press releases and their comms teams, and I'm talking about social media postings, because our generation and generations after me use social media to get our message out there.
"You see it with legislation, with the direction that we run our office in," she says. "And then obviously I had a baby, so we're working on legislation to really change how things run around here."
Luna was elected in 2022 as the youngest Republican in Congress, with the help of an endorsement from Trump.
"I think [former] President Trump really has an eye for younger talent," she says. "Kudos to [former] President Trump, because had it not been for him, I probably wouldn't be here right now."
She's also a member of her party's hardline "Freedom Caucus", has called herself a "pro-life extremist" and believes the 2020 election was stolen.
The ABC asked each of the 10 youngest members of Congress for an interview. Luna was the only one to agree.
Very much on the other side of the political debate, Joe Vogel isn't in Congress right now, but he wants to be.
The 27-year-old was unsuccessful in the Democratic primary election for one of Maryland's congressional districts held in May.
Luna and Vogel would probably disagree on almost everything, but not on the role of young people in politics.
"My commitment is to making sure that we have more young folks join in [and] be part of this process," Vogel says.
So what's keeping young people out?
Congress may have aged along with the population, but for the representation gap to be this large there must be something else keeping young people out.
There's at least one structural factor pushing up the average age a little bit: minimum age limits.
You're not allowed to run for the House of Representatives in the US until you turn 25, and you have to be 30 to run for the Senate.
Should there also be a maximum age limit? Stockemer thinks it's worth putting on the table.
"There's a retirement age for a lot of people … so we should also ask the question," he says. "We talk about retirement in basically any other field, but not in politics."
It's actually a popular idea. An overwhelming majority of voters for both parties agree that there should be an age limit for elected officials.
[DATAWRAPPER A majority of US voters want politician age limits]But that's easier said than done: instituting age limits in politics would require constitutional change.
Daniel Bessner points to a general "unwillingness to address death".
"We're not a country that loves thinking about or talking about death. There's a culture of the eternal present in this country, not really in a Zen way," he says.
"That certainly leads people, whether you're talking about Strom Thurmond or Dianne Feinstein or Ruth Bader Ginsburg or Joe Biden or Nancy Pelosi, to spend their final years on Earth working incredibly hard in an incredibly difficult position where that would not necessarily have been the case in other cultures."
Then there are the cultural barriers excluding young people.
Luna points to the difficulties people with young families have serving in national office: "The travel schedule can be pretty harsh … half of the week, every week for the most part, we're up in Washington, DC."
"American politics is the last known blood sport. I think that politics around the world can get nasty, but especially here in the states, I feel like it's gotten significantly worse with the rise of social media."
And that's before you even get elected, she says: "[You] campaign for two years to get elected. A lot of people can't take time off from work to do that."
Then there are the views on the maturity or effectiveness of young people in politics that Joe Vogel is keen to dispel. "The people who sent me here gave me a tremendous opportunity, but it was also a test," he says.
"[They said] 'We want someone with those lived experiences', and now my commitment is to showing the people that sent me here that yes, I can get things done. I've been very committed to demonstrating that young people can be effective and accomplished legislators."
And then there's the money issue. Running for congress costs a lot, and it's only getting more expensive.
On average, winners of congressional seats in 2022 spent about $US2.8 million on their campaigns.
[DATA WRAPPER running for an election is expensive] The money doesn't usually come directly from the candidate's pocket, but it has to come from somewhere.
"You need to have the connections, the networks," Stockemer says. "It's rather hard for young people to have that."
Vogel says a lot of his colleagues have other high-paying jobs, or they own businesses or real estate. "They have other ways to sustain themselves," he says.
"I don't have that, right? I have $40,000 of student loan debt that I'm still paying off."
Is a change on the way?
If you scroll back up and look at the overall average age of American politicians, you'd see that while this congress is one of the oldest on record, the rapid aging in the chamber appears to have been arrested.
Take a look at the average age of new members when they first enter congress.
[DATA WRAPPER Congress' class of 2023 is the youngest in decades]Like the overall chamber, we'd seen an aging trend in each freshman class.
But it peaked in 2017, and the class of 2023 has a median age of 46.3, the youngest it has been in more than two decades.
It could be that we're seeing the beginning of a turning point, but if so, it's not happening quickly.
Because once someone is elected, they tend to leave when they're ready, which for most politicians is more than a decade.
"In the US, over 90 per cent of representatives get re-elected from one election to the next," Stockemer says. "And hence, a lot of people, they have their seat and they can stay forever."
That incumbency advantage is a handbrake on any change, but young politicians hope it is coming.
"Every time I see young folks here in the hallways … I'll take them with me to the house floor and I'll have them sit in those seats with me," Vogel says.
"I'll show them how everything works … make them really envision themselves in those settings.
"Because I think when young folks envision themselves in those settings, they start seeing it as possible for them to get engaged and be part of this work."
Perhaps those efforts are starting to pay off.
"I don't want to do this forever," Luna says. "At that age, I hope that I'm on a Florida beach, nowhere near Washington, DC."
