The massive 500-ton cranes gently lifted the Jim Crow-era rail car high into the air.

Constitution Avenue had been closed since early Sunday morning to make way for the artifact, which was slowly lowered into the construction pit of what will become the Smithsonian’s National Museum of African American History and Culture.

Tourists, passersby and history buffs took pictures of steel and shrink-wrap and machinery. Onlookers pressed against the fences and peered through binoculars, straining to get a better view. They took pictures of themselves taking pictures of history being made, just to say “I was there.”

There to see the 44-seat Southern Railway car, which required its black passengers traveling into the pre-civil rights South to contort physically and psychically in order to conform to the smallness of their second-class citizenship....