Now that @SecBlinken is confirmed as the US Secretary of State, here are some things I found out about the job.

For a start, it's the oldest Cabinet post. There was a Secretary of Foreign Affairs, as the job was once called, before there was a President, with Robert Livingston appointed in 1781.

If the United States had a Prime Minister, the Secretary of State could be considered that person. They are the most senior member of the Cabinet, and higher in the line of succession than any of their colleagues. Interestingly, they once had a much stronger domestic role.

Once upon a time, especially in the early days, the Secretary of State was kind of the manager of government affairs for the President. The name itself derives from the titles used by British Cabinet ministers, and belies the formal job, which is about foreign relations.

The State Department used to be in charge of administering the US Census, and also once looked after the US Mint (you'd think that would be Treasury, which today it is). Most of these domestic jobs have now been moved on, but a few remain.

One of those is that the Secretary is the formal custodian of the Great Seal of the United States, which sounds like they're a zookeeper. It just means they look after the use of the seal, on diplomatic documents and so on.

As a remnant of the days when the Secretary was a domestic officer, it's to them, not the Speaker or anyone in Congress, that the President and Vice President resign. Nixon's resignation letter in 1974 was addressed to his Secretary of State, Henry Kissinger.

Interestingly, Kissinger was both Secretary of State and National Security Adviser at the same time. Holding multiple government posts is relatively common in the UK and Australia, but in the US it's considered very unusual.

Because the Secretary of State is such a crucial adviser to the president, they're almost always someone close to the president whom the president can trust. James Monroe, during the War of 1812, was James Madison's secretary of state AND secretary of war simultaneously.

The Secretary of State is obviously very prestigious, and it used to be considered THE job you wanted if you wanted to be President. Six Secretaries were elected President later on, all of them before the Civil War. Never mind the Vice Presidency - it was State everyone wanted.

In the days since, though, several former Secretaries have either run for president later or, more commonly, been appointed after their failed run. These appointments are political but having a high-profile person in the job, especially a rival, helps a president's image.

Both of Obama's Secretaries of State were former Senators who had run for president - John Kerry and Hillary Clinton. Other prominent candidates like Charles Hughes, Ed Muskie and William J Bryan had also been Secretary of State after their run.

Hillary Clinton was the first former Secretary of State to run for president since 1988 but the first to get the nomination since 1884. So not so much of a stepping stone these days.

Of the Secretaries that have served in the last fifty years, very few have been career politicians. Most have been officials and civil servants, and/or political advisers and staffers. Some served in other Cabinet roles. Only four were ex-politicians, including Kerry and Clinton.

The first African-American secretary of state (Colin Powell), and the second (Condi Rice, also the first woman) were appointed by GW Bush.

Condi Rice was, pardon me, the second woman and first black woman in the role. The first was, of course, the incomparable Madeleine Albright.