African-American pioneers who broke barriers
The Smithsonian's National Museum of African American History and Culture features several exhibits of firsts, from the memorabilia of President Obama, the first black president, to the uniform of Jackie Robinson, who broke Major League Baseball's color barrier. We spoke with five others who were also firsts in their respective fields -- Bob Johnson, Michelle Howard, Eric Holder, Mae Jemison and Ernest Green -- about their pioneering spirit.