Brent D. Glass, the director of the National Museum of American History for the last nine years, announced Monday he is retiring in July.

Glass, 64, led the museum through a two-year renovation of its core area, creating an open public space and a new display of the Star-Spangled Banner. The museum, the third most popular of the Smithsonian complex, was closed during that time.

In a phone interview, Glass said he was satisfied that the museum had achieved the goals of a Blue Ribbon Commission that had sharply criticized the museum as confusing and staid.

“The biggest achievement was the master planning and the physical transformation and the intellectual transformation of the museum. We placed the major objects in a historical context and talked about the story behind the objects,” Glass said.

His decision to retire, he said, was prompted by wanting to promote history education in a different way. “I have a lot of different ideas on how I want to be most effective in promoting history education and public memory,” said Glass, who will remain a senior adviser at the Smithsonian until the end of the year.

Glass didn’t give specifics about a future job but said he had been brainstorming. “David McCulloch is a very good friend and he has been so active about taking history education to the forefront. There are people like Sandra Day O’Connor and Richard Dreyfus, who among others, are talking about the lack of knowledge about history. I think I can have a more direct impact,” he said.

Glass said his work with the U.S. Flight 93 Memorial Advisory Commission also influenced his decision. “That was instrument in my concern about how we develop our historic memory and that also goes back to my work with Gettysburg Battlefield,” he said. Before coming to the Smithsonian in 2002, Glass was executive director of the Pennsylvania Historical and Museum Commission.

The Smithsonian's National Museum of American History is performing a specialized conservation treatment to ensure the long-term preservation of Thomas Jefferson's Bible. (Hugh Talman, National Museum of American History)

Since it reopened the museum has attempted to have more “living history” events. Glass said the daily folding of a replica of the Star-Spangled Banner during the summer is a moving event. “The interns unfold the flag. And then 50 or so people take a section and fold it up. And people are taking pictures and singing the National Anthem. It’s moments like that that are very reassuring,” said Glass.

The American History museum has about 3 million artifacts and is constantly adding to its archives. Among the most famous are Dorothy’s ruby slippers from “The Wizard of Oz;” Julia Child’s kitchen; the Woolworth’s lunch counter, the site of the first student sit-in protest and the portable desk Thomas Jefferson used to write the Declaration of Independence.

Glass said one of the important donations during his tenure was the firefighting memorabilia from the 19th Century, given by the Cigna company.

But he said the popular culture gifts, which draw a lot of attention, were significant too. Included would be Jerry Seinfeld’s puffy shirt from the television show and a gown from the Grammy Awards that Nancy Wilson donated recently. “You can’t have more fun than being director of the American History museum. You have so much variety. You get to solve problems of consequence. And I like to say we are in the forever business.”