It is perhaps inevitable that when you walk around the Tidal Basin dressed in the blue woolen uniform of a Union soldier, most people are going to edge away. They will give you a wide berth, convinced you are going to ask them to sign a petition.

But a few are going to approach, intrigued, especially if you’re carrying a placard that reads, “Attention! Take the Civil War Quiz.” They will be people like Granville Harlow.

“Honey!” he announced to his wife, who had wandered ahead with their two children. “I’m taking a Civil War quiz. Washington Post.”

Perhaps it is hard to stump people whose names make them sound like transplants from the 1860s. And so it was with Granville Harlow, a business consultant from Minnetonka, Minn. When I asked him who fired the first shot of the Civil War, he gave me the name of the Confederate general who ordered the bombardment of Fort Sumter: P.G.T. Beauregard.

I was looking for which side fired first: the South.

“The battle lasted two days,” Granville added, correctly.

The only thing I could fault him for was his pronunciation: Fort “Sumtner.” But that might just have been Granville’s Midwestern accent. An elementary school teacher from Osawatomie, Kan., did the same thing.

That was Christy Levings. Which side fired first, Christy?

“Oh goodness. I have to think about that. I want to say the Confederates fired first.”

You would be right to want to say that.

And which side won that first battle? I’m asking you, Jim Knickerbocker of Michigan.

“I’m going to go with the South,” Jim said. “If the North had won, it would have been over. [The South] would have said, ‘Okay, never mind. We’ll behave.’”

We’re so knowledgeable about the Civil War around here — surrounded by battlefields, caught up in textbook controversies, steeped in what seems like unfinished business — that I sort of figured the reverse must be true: People from the rest of the country must not know anything about it. I mean,Minnesotans didn’t have anything to do with the Civil War, did they?

“Oh, yes, they did,” said Granville. “The 1st Minnesota in Gettysburg, we plugged the hole on day three and saved the day.”

Did Michigan fight?

“Sure, we did,” Jim said.

“Actually,” said his wife, Linda, “if you go to Gettysburg you can see several monuments from the regiments from Michigan that fought there.”

That doesn’t mean that the narrative of the war is the same regardless of where you’re from.

Christy, the teacher, lives three miles from the Kansas cabin that John Brown stayed in when he organized raids against slavery supporters in 1856, killing five.

“We look at John Brown in Kansas as a terrorist,” she said.

Bleeding Kansas. The Sack of Lawrence. The Pottawatomie Killings. Maybe the Civil War didn’t start at Fort Sumter after all.

National Air and Space Museum staffers Mychalene Giampoli and Tim Grove were out for a lunchtime stroll when I badgered them into taking the quiz. Who fired the first shot of the Civil War?

“The South,” Tim said. “I don’t remember the name of the person.”

Tim did just fine on the quiz, but what he and Mychalene really wanted to talk about was something else: This summer, Air and Space will mark the 150th anniversary of the day that “aeronaut” Thaddeus Lowe inflated a gas-filled balloon on the Mall. It was a demonstration for President Lincoln, who immediately grasped its military applications.

“I hope you’ll encourage people to come to our fabulous event in June,” Mychalene said.

Steven Walsh of Long Island, N.Y., came up to me, eager to take the quiz. When I asked him where and when the Civil War started, he said, “I just read this in Smithsonian magazine.”

It’s the cover story in the latest issue.

This is the sort of town Washington is: a place full of people who read Smithsonian, go to the Smithsonian or work at the Smithsonian.

The quiz-takers all wondered what their prize was for doing so well. There wasn’t one. Knowledge is its own reward.