Boise: It's not just presidential candidates who are old.

According to my own data, nearly 20 percent of members of the House and Senate are 70 years old or older, compared to about 6 percent who are under 40 years old.

North Dakota voters recently approved a ballot initiative that would impose an upper age limit on that state's congressional candidates. If it survives potential court challenges, the law would prohibit anyone 81 or older from serving in Congress from North Dakota. The motivation behind such a move: correcting that significant generational imbalance in Congress. With the number of high-profile American politicians approaching or exceeding 80, including presumptive presidential candidates from both parties, it is no surprise that moves like Dakota's of the North are receiving attention.

But what exactly explains the advanced age of Congress? And what, if anything, could help balance things between generations?

Some Fundamental CausesThe advanced age of Congress has many causes, and some of them are inevitable.

First, if it seems like Congress continues to age over time, it's because Americans do, too. According to historical data on members of Congress, the average age of House members has increased 10 percent since 1960: 58, up from 52. A similar increase occurred in the Senate, with an average age of 63, up from at 57.

But the life expectancy of the average American (79 years, up from 70) increased even more during this time, about 13 percent. And according to the U.S. Census Bureau, the American median age rose even more during that time, more than 30 percent, from 30 to 39. While North Dakota proposes an age limit of sorts, the U.S. Constitution The United States already imposes a minimum age limit. Members of the House must be at least 25 years old when taking office; senators must be 30 years old. So if the average ages of congressmen cited above seem high, it is in part thanks to some artificial inflation of age floors.

It is difficult to find young candidates

But natural tendencies and constitutional requirements do not fully explain why younger generations are so underrepresented in Congress. An additional big reason is that younger potential congressional candidates face a steeper climb and must make greater sacrifices than older candidates.

For example, even if they are interested in running for Congress, Americans in their 20s and 30s haven't had as many opportunities to establish themselves in secure careers as older generations. This means less access to the political networks and connections that political science research shows are crucial to the success of congressional campaigns.

More importantly, this means less access to money and potential donors. When I spoke last year with U.S. Rep. Maxwell Frost, a Florida Democrat – the first Gen Z member of Congress – he explained why his success was the exception and not the rule. “It's really hard,” he told me. Frost. "The system is not created for young people to run for public office." Just being a candidate, he said, means “a year without a salary. If you're already rich, that's no big deal; you're fine, you have savings. It makes young people unable to run.”

Young potential candidates also face a time deficit as well as money. Compared to later years, the 20s and 30s typically contain more major life events and changes, such as career transitions, geographic mobility, and starting a family. As a result, politics takes up less space in the lives of young people, compared to older generations, who have more time, personal stability, and professional and financial security.

Age Has AdvantagesMeanwhile, older Americans interested in running for Congress enjoy some key electoral advantages.

Older age brings with it longer careers – political or otherwise – that voters often interpret as proven experience, or longevity in jobs that may well translate into effectiveness as a member of Congress. In other words, older generations have had more time to prove themselves to voters. Younger candidates may seem inexperienced by comparison.

Political science has also established the difficulty of unseating incumbents in Congress. Almost all members of Congress who run for re-election end up winning. The so-called “incumbency advantage” helps all sitting members of Congress, not just the oldest members. But it limits the number of open seats that are most likely to attract younger generations to Congress. Are there solutions?

Frost and others emphasize the importance of generational balance in Congress for both representation and lawmaking.

The good news is that any progress made in this area will pay off in the future. Political science findings indicate that seeing people “like us” in Congress or other positions helps us feel adequately represented and see our political institutions as more legitimate. The success of younger candidates encourages other young people to take the leap themselves, starting a virtuous cycle of representation. Although some of the factors favoring older candidates are inevitable, there are things that could be done to encourage young people to run for public office. In our conversation, Frost suggested allowing candidates to draw more generous stipends from their own campaign funds to ease the burden on younger, less financially viable candidates. And, of course, age limits like those in North Dakota could help leave room for younger generations to apply. (The conversation)

GSP