Herman Cain’s usually ebullient face was blank at the beginning  of the tour of the African-American Museum of Iowa in Cedar Rapids. Standing before a large, sparkly and heavily accessorized African icon, the black Republican presidential aspirant — polling 3rd in the state with 10 percent — pulled his chin low and seemed to aim his gaze over his glasses frame. Utterly affectless, Cain studied the piece.

Watching Cain intensely was an entourage of almost 30 people made up of press, campaign and museum staff, all white but for a stylish and very quiet black woman who, it turned out, worked at the museum. The group was going to see the permanent exhibit on African-Americans in Iowa, which has been on view, in one form or another, since the museum first opened in 1998. (It closed for about a year after the 2008 flood.)

When Cain blinked and stepped away from the imposing African sculpture, Michelle Poe, the museum’s young, energetic — and white — education director, took it as her cue to swing around him and point to a map of Africa.

“Africa is a continent, not a country,” she said.

And this Cain couldn’t resist: He laughed aloud.

But Poe was unflustered. “I do a lot of tours for kids,” she said, “and, believe me, that’s important to say.”

Poe then led Cain through an arch doorway she explained as a portal of no return, similar to doorways in slave ports such as Goree Island, in Senegal.

“So is there a real door like this?”Cain asked, looking up at the arch. He stepped through it and turned to the press people. “I like to ask questions. It’s what I do,” he said grinning.

Poe pulled the party quickly through the hallway that depicts the Middle Passage (unfortunately labeled “The Miserable Journey”), and went right for the more uplifting stories. There was an exhibit on York, the first African-American recorded in Iowa, who helped Lewis & Clark and was initially denied his freedom by Clark. And there was Ralph, who came to Iowa with permission from his master to buy his freedom.

“But when he didn’t have enough money, his master sent slave hunters after him,”Poe said. “Ralph sued and the people of Iowa rallied around him.”

Ralph won his case, she said, which set precedents cited in the historic Dred Scot decision. In fact, listening to Poe, it was easy to get the sense that Iowa — which currently has a black population of 3 percent — was way ahead of the curve on civil rights, especially on education and integration.

One of the biggest exhibits, in fact, mimics the lunch counter at Katz’ Drugstore in 1949 Des Moines, where the owner, fined over and over because of his refusal to serve black customers, inspired constant sit-ins.

“This was in 1949,” emphasized Poe, “long before the more famous sit-in in 1960 in Greensboro, South Carolina.”

This was clearly news to Cain, who obliged photographers by sitting at the counter before the plates of plastic food. Light flashes covered him as he read the story on the exhibit wall, his eyebrows arching over his glasses. He placed his hand on his chin in classic thinker-style.

“This is very informative, very informative,” he said, subdued.

But what really stopped Cain in his tracks was a pair of doors midway through the exhibit, one labeled “Whites only,” the other “Colored.”

Cain crossed his arms around his chest and grinned. “I remember those,” he said. “I remember them from when I was growing up in Georgia.”

Then swinging his arms from side as if he as going to run, he said, “Watch this, y’all,” and mock-sprinted through the “Whites only” door.

“The great thing about this country is its ability to change,” a triumphant Cain declared, gathering the small group around him to explain his belief in America’s transformative powers.

And then Poe provided the story to prove his point. “We had a group of school kids recently,” she said, “and after I explained the exhibit to them, a little boy raised his hand, incredulous, and said, ‘But that’s racist!‘ And I said, ‘Yes, that’s racist’.”

Cain laughed. “See what I mean?”

Cain came to another halt when they got to the museum’s last piece, a giant photo mural of Barack Obama celebrating his victory in the Iowa caucuses. A campaign podium used by Obama was set in front of it.

As if suddenly remembering her guest, Poe said, “Whatever your views of Barack Obama, what he did here was historic.”

Cain quietly appraised the bigger than life photos of a much younger and vigorous Obama. “It was historic,” he said, nodding in agreement,“it was indeed historic.”

After the tour, Cain hung out with the press for a bit in the front foyer, joking about how the museum will have to make room for his campaign podium after he wins, and how it’s still a surprise to walk through a “Whites only” door “and not get shot.”

But minutes later, he was rallying about 100 Iowans in the museum’s public hall. Among them was Pamela Fisher, 53. She voted for Obama in 2008 but is looking for someone new. But for Cain himself, Fisher was the only African-American in the room.

“It’s a little strange to be only black person here, yeah, but … not really,” she said, correcting herself. “I mean, I’ve lived in Iowa my whole life, you know what I mean?”