In 2007, candidate Barack Obama, drawing rockstar crowds on his way to the White House, held a rally on Boston Common that drew 10,000 people. It was the biggest political gathering in Massachusetts in decades. On Saturday, Bernie Sanders brought more than twice that number, an estimated 24,000, to the Boston Convention and Exhibition Center — close to 20,000 inside the cavernous building and the rest watching a big screen outside.

One photo showing the scope of the event, posted by AlterNet writer Zaid Jilani, got the attention of a lot of political reporters: