WASHINGTON — Not far from the Washington Monument, Lonnie Bunch is standing on a deck outside a trailer, looking down on what for two years has been a construction pit on the National Mall.Now it has the emerging shape and promise of a new museum.“It’s humbling,” said Bunch, the founding director of the new National Museum of African American History and Culture. “For the last 8 1/2 years, it was my job to make people believe.”As Black History Month draws to a close, construction is at the midway point for what will be a permanent symbol of the role of African-Americans throughout U.S. history.The grand opening is expected by the end of 2015 or in early 2016, perhaps during Black History Month, though for Bunch, “Every month is Black History Month. And for the Smithsonian, it’s going to be for millions of people.”Officials with the museum, part of the Smithsonian Institution, say they have raised about $400 million toward the $500 million cost, including more than $160 million from private sources. A significant contribution — $12 million — came from media mogul and actress Oprah Winfrey, who will have a theater inside the museum named in her honor.“By investing in this museum, I want to help ensure that we both honor and preserve our culture and history so that the stories of who we are will live on for generations to come,” Winfrey said last year.President Barack Obama, the first African-American chief executive, attended the groundbreaking two years ago. But as Bunch raised money and developed the collection, he had to make sure people believed that the museum would be built.“I get very emotional when I come here,” he told McClatchy on a recent tour of the site.It could very well be the last building to go up on the mall, sometimes referred to as the “nation’s front lawn.” Mall advocates, from Congress to the National Park Service to arts experts, seem to agree that nothing more can be placed along the nearly 2-mile corridor from the Capitol to the Lincoln Memorial without detracting from the green space and the array of museums and memorials.The Smithsonian will use its empty Arts and Industries Building for a National Museum of the American Latino, still awaiting congressional approval.‘Hiding in plain sight’Phil Freelon, the African-American architect from Durham, N.C., who designed the building, imagined an angular, three-tiered boxlike structure with 10 stories — five above ground, five below.The exterior will be layered with 3,600 bronze latticed panels — “coronas” — to make it gleam, inspired by the decorative ironwork crafted by slaves in Charleston, S.C., and New Orleans.“The skin of the building,” Bunch said, calling the overall design “an homage to those hiding in plain sight.”One of the goals is to provide a sense of the struggles and successes of African-Americans. Museum-goers will cross a water feature to recall the experience of slaves crossing the ocean to come to America.From its site near the Ellipse, the building offers vistas that extend across the Potomac River to Arlington National Cemetery in one direction and to the Capitol in another.Bunch, who went up in a cherry picker to see the views for himself, said, “We wanted to have that right tension of the building and one of the most sacred spaces in America.”Big artifactsSome large artifacts have already been put in place — shrink-wrapped for now — so that the museum can be built around them.A railroad car with different compartments for whites in the front and a sign for “colored” in the back has been restored. It serves as a compelling example of how the Jim Crow-era segregation laws separated blacks and whites in public facilities. Jim Crow was a derogatory term for African-Americans.Visitors can walk through the vintage 1918 Southern Railway car, used from 1940 to 1960 on routes in Kentucky, Tennessee, Georgia and Florida, and see the comfortable seating for whites and the divider that kept African-Americans in the basic seating in the back.“This rail car … is a tangible remnant from America’s long years of segregation, and those remnants are rare,” said Peter Claussen, chairman and CEO of Gulf & Ohio Railways, who donated the rail car to the museum and who is also a member of the Smithsonian National Board. “The separate water fountains are gone. The black and white sections of movie theaters are gone. There are very few objects that allow people to see what segregation was like, and this is one of them.”There’s also a 21-foot concrete guard tower from Angola prison, the Louisiana State Penitentiary, that was built in the 1930s and to Bunch serves as a powerful symbol of the oppression of African-Americans.Many were rounded up as vagrants and, in a practice of “convict-leasing” that began at the turn of the 20th century, “it became a way to reinstitute slavery,” Bunch said, explaining that prisoners were leased out to work for residents.The guard tower and the railway car will be featured in the museum’s Segregation Gallery as part of an inaugural exhibition, “Defending Freedom, Defining Freedom: Era of Segregation 1876-1968.”Slave cabinA slave cabin from Point of Pines Plantation on Edisto Island, S.C., dating to the early 19th century, will tell a similar tale of life during slavery. The clapboard cabin, which will display the narrow confines of slave life, was dismantled piece by piece and shipped to Washington in May. It will be reassembled for an exhibition called “Slavery and Freedom” when the museum opens.Some artifacts intended for the museum are now displayed in a temporary space in the Smithsonian’s National Museum of American History, across from the black history museum’s 5-acre site.For Bunch, who started out in 2005 with just two staffers and no artifacts, and others who have devoted their lives to creating a museum to honor African-Americans, their long-sought goal is within reach.“You want people to go into this museum and be changed,” he said.