Lonnie Bunch is the founding director of the Smithsonian Institution’s National Museum of African American History and Culture, set to open in September on the Mall. (Jahi Chikwendiu/The Washington Post)

Lonnie Bunch has thousands of decisions before him — and exactly 235 days to make them.

The founding director of the National Museum of African American History and Culture announced Monday that the museum will open Sept. 24 — with President Obama cutting the ribbon.

Although the opening is within sight, Bunch remains focused on the hurdles along the way.

Design issues pop up daily. There are staffing questions, including what jobs to fill and whom to hire. And details about the opening ceremonies continue to be hashed out.

There’s about $40 million left to raise — a small percentage of the $270 million needed, but still a big nut. Then there’s the task at the top of Bunch’s to-do list: moving more than 3,000 objects featured in the 11 inaugural exhibitions — from Chuck Berry’s Cadillac to Harriet Tubman’s hymnal — into the 400,000-square-foot building on the Mall between 14th and 15th streets NW.

“The problem is it’s been a 10-year sprint instead of a 10-year marathon,” Bunch said. “You run and you think you’re close to the goal line, but you’re not. You’ve run 80 yards, but there’s still 20 to go.”

[Finish line in sight, African American museum still seeks money and objects]

Construction on the building was underway last summer. Museum officials hope work will be completed in April. (Andrew Harnik/Associated Press)

Construction is nearly finished, and Bunch expects the scaffolding to be removed and workers to leave by early April. At that point, the installation of the artifacts and other materials will shift into overdrive. Now, Bunch said, only objects that can withstand the less-than-pristine environment — such as Berry’s candy-apple-red car — can go in. After the interior conditions are improved — dust and humidity are the enemies — the staff will install the rest.

It will be a massive effort, and one that keeps Bunch up at night.

“It’s a puzzle. It’s not as numbingly linear as I would like,” he said.

Some artifacts are still being prepared for display, while others await specially designed cases. There also are graphics and labels and 134 video and audio components to be installed.

“Doing exhibitions is like putting on theater,” Bunch said. “Two days before, it looks like hell, but when the public walks in they think it’s been like that for months.”

The backstage theatrics are being completed in a sprawling warehouse about 12 miles from Bunch’s office in suburban Maryland. There, in a temperature- and humidity-controlled conservation lab, dozens of staff and hired specialists are racing to get the stars of the museum ready for their spotlight.

Reneé Anderson, the museum’s head of collections, is overseeing the effort, which involves reviewing the condition of every piece, making repairs when necessary and ensuring that everything required for display is ready. After that, the artifacts will be wrapped for transit and then — finally — carefully transported to the museum.

In the lab, there are blue exhaust tubes and bright lights extending from the ceiling over the half-dozen work spaces. Conservators work on paintings and other fragile items in one corner and on large, wooden pieces in another.

Reneé Anderson, head of collections, shows Rex Ellis, associate director for curatorial affairs, the work that has been done on a Civil War era rifle-musket owned by Walter Denning. The weapon is one of more than 3,000 artifacts being prepared for display in the museum. (Jahi Chikwendiu/The Washington Post)

The work is both art and science. Anderson, wearing protective gloves, handles a Civil War-era rifle that will be on view in the military history gallery. Complete with a ramrod and collapsible sight, the weapon was used by a member of the 26th Regiment, an African American combat unit. The gun has been repaired, but it’s by no means perfect.

“We don’t want to take away the wear, the physical manifestations of its age and what it’s been through,” Anderson said.

Other objects must be conserved to protect them from future decay. A guest book from a vacation cottage on Martha’s Vineyard that hosted well-to-do African American families in the 1930s has been taken apart and, after tape and other residue are removed from the fragile paper, will be put back together. On another table, a technician is working on Item No. 2014.30.3 — Roy Campanella’s catcher’s mitt — to fix the stitching on the leather flap.

Some display issues have yet to be resolved. If the trunk owned by one of the first Tuskegee Airmen pilots killed in action in World War II will be left open, it will need support to keep it from harm.

Anderson handles a Buffalo Soldier Bible from about 1913 and a 1966 pamphlet for the Black Panther Party of Lowndes County, Ala. (Jahi Chikwendiu/The Washington Post)

Linda Landry, from left, Anderson and Laura Manaker examine a 1971 horse saddle used by Ernie Robinson, one of the founders of the Black Stuntman’s Association. The saddle is part of the museum’s 35,000-piece collection. (Jahi Chikwendiu/The Washington Post)

Bunch will be closely monitoring the effort as it ramps up over the next few months. He’ll also review each of the video pieces that will complement the historic items as well as every aspect of the exhibitions’ final design.

Then there’s that $40 million left to raise. Last month, a $10 million gift from Smithsonian regent David Rubenstein was announced, followed by a $1 million donation from Wells Fargo.

“You want to finish the campaign stronger than you started,” Bunch said of the large donations. Rubenstein’s gift was timed to help that effort.

“I wanted to help get the fundraising completed before the museum opens and am hoping others might follow suit,” said Rubenstein, co-CEO of the Carlyle Group.

Two enslaved women and their children appear in a photo taken by a Union soldier near Alexandria. (Smithsonian National Museum of African American History and Culture)

September’s opening ceremonies are another priority. Bunch and his staff are figuring out how many activities to schedule around the opening week or weekend, and how many to stretch out over the inaugural year. And the museum’s 175 employees, now in offices on Maryland Avenue SW near the National Air and Space Museum, must be moved into the new building. Bunch is well aware that no matter how well prepared they are, the final months will be taxing.

He wrestles with how to keep up staff morale and help them recognize their “amazing” work.

“In eight months,” he says he tells them, “you will have the president of the United States open your museum. Take a breath and enjoy it.”