How many people have been president of the United States?

History surrenders this secret grudgingly. Several people technically were president, but aren’t considered presidents of the United States. You have to look hard to find them, but they’re there.

For example, George H.W. Bush was acting president for almost eight hours in 1985 while Ronald Reagan had colon surgery. Dick Cheney did likewise in 2002 and 2007 when his boss, George W. Bush, was anesthetized for colonoscopies. The 25th Amendment was also invoked for Kamala Harris for 85 minutes on Nov. 19, 2021, when Joe Biden was under anesthesia.

Then there was David Rice Atchison, who may — or may not — have been president for one day in 1849.

With another Inauguration Day upon us, it’s the perfect time to revisit the most obscure “Substitute-in-Chief” story of all.

Harry Truman never wanted to be president. He got the job anyway when Franklin Roosevelt died in April 1945. FDR was a hard act to follow, and Truman was largely unknown outside his home state. Would he be up to it?

He jumped in with determination and made one major decision after another: approving the Marshall Plan, the Berlin Airlift, and the use of an atomic bomb — twice.

Harry clearly could handle the job.

Yet, when election time rolled around in 1948, the odds were overwhelmingly against him. Democrats had held the White House for 16 years, and many folks wanted a change. Republican Tom Dewey was a tough challenger. Virtually nobody gave Truman any chance of winning. Public opinion polls, national columnists and political insiders unanimously said Truman would be buried in a landslide. Everyone agreed.

Except for Harry Truman.

He shrugged them off, hopped aboard his campaign rail car, the Ferdinand Magellan, and logged 20,000 miles over several grueling weeks. (By comparison, that’s almost one trip around the Earth.) He stopped to speak in any town, big or small, where people wanted to hear him.

And that down-to-earth strategy worked. On Election Day, he pulled off one of the greatest upsets in American political history. The Man from Missouri had done what literally everyone said was impossible.

So naturally, Truman was more than ready to savor his triumph on Inauguration Day.

A huge crowd turned out on Jan. 20, 1949. An additional 10 million watched in 14 cities on the brand-new invention of television. More people saw Harry Truman being sworn in that day than had witnessed all previous presidential inaugurations combined.

However, there was a bad mistake. And not surprisingly, it was Congress’ fault.

The Constitution specifies the president’s term begins at noon on January 20. Exactly four years later, it expires. At 12:01 p.m., he’s no longer president. Which is why the inauguration ceremony is timed to the minute so the oath can be administered precisely at noon.

That didn’t happen in 1949. Members of Congress were 10 minutes late arriving at the Capitol’s East Front. (The ceremony wouldn’t be moved to the more spacious West Front until 1981.) They took an additional 10 minutes to find their seats. When the program finally began, it was 20 minutes behind schedule.

Incoming Vice President Alben Barkley took his oath first, as tradition dictated. He wasn’t sworn in until 12:23. Since Truman’s term had officially expired 23 minutes earlier, the office of president was vacant during that time. As the constitutionally designated presidential successor, Barkley was the acting president of the United States.

A long prayer and much hot air followed. Harry finally put his hand on the Bible at 12:29.

Technically, Truman was a private citizen during that six-minute gap.

In a practical sense, it didn’t matter much back in 1949. The Age of Terrorism was decades in the future, and while the Atomic Age had begun, there were no intercontinental missiles or long-range bombers to allow the Soviet Union to take advantage of the situation.

All this is a technicality, of course. However, lawyers wouldn’t exist without technicalities, and many presidential legal scholars (yes, there are such critters) agree that for those six minutes on Jan. 20, 1949, Alben Barkley technically had the authority, if not the office, of the presidency.

You can stump your friends with this bit of arcane trivia at your next neighborhood barbecue. And if you ever happen to be elected president yourself one day, make sure Congress shows up on time.

J. Mark Powell is a novelist, former TV journalist and diehard history buff. Have a historical mystery that needs solving? A forgotten moment worth remembering? Please send it to HolyCow@insidesources.com.