Why are US politicians so darned old?

It’s not just presidential candidates who are old.

Based on my own data, nearly 20% of House and Senate members are 70 or older, compared with about 6% who are under 40.

Voters in North Dakota recently approved a ballot initiative that would place an upper age limit on candidates for Congress from that state. If it survives likely court challenges, the law would bar anyone 81 or older from serving in Congress from North Dakota. The motivation behind such a measure: to correct that major generational imbalance in Congress.

With a number of high-profile American politicians approaching or exceeding 80, including both parties’ presumed presidential nominees, it’s no wonder measures like North Dakota’s are getting attention.

But what exactly explains Congress’ advanced age? And what, if anything, could help even things out between the generations?

Some core causes

Congress’ advanced age has many causes, and some of them are unavoidable.

First, if it feels as though Congress just keeps getting older over time, it’s because Americans are, too. According to historical data on members of Congress, the average House member’s age is up 10% since 1960 – 58, up from 52. A similar increase happened in the Senate, with the average age 63, up from 57.

But the average American’s life expectancy – 79, up from 70 – is up by even more during this time, around 13%. And according to the US Census Bureau, the median American age is up by even more during that time, over 30%, from 30 up to 39.

While North Dakota is proposing an age ceiling of sorts, the US Constitution already enforces an age floor. Members of the House must be at least 25 years old by the time they take office; senators must be 30. So if the average congressional ages cited