Their most recent addition is the flowing, one-shoulder white gown Michelle Obama wore to the 2009 Inaugural balls.
Obama said the exhibit showcases history in a real way.
"When we look at the gown that Jackie Kennedy wore 50 years ago or the one that Mary Todd Lincoln wore 100 years before that, it really takes us beyond the history books and the photographs and helps us understand that history is made by real life people," said Obama.
In total, the ongoing exhibit will feature a total of 24 dresses, portraits, White House china, and personal possessions of several first ladies.
The gallery is part of the already popular "First Ladies at the Smithsonian" exhibit.