Chopper 6 was over the center hours earlier, and captured lines wrapped around the building that stretched nearly a mile long and a number of people wide.
RAW VIDEO: Huge line forms for Sanders rally
Earlier in the day, 200 people attended an invitation-only community event at Tindley Temple United Methodist Church on South Broad Street to hear Sanders speak.
Many of those in attendance told Action News they have already made up their mind. They are voting for Bernie Sanders, not Hillary Clinton.
After winning the last seven of eight presidential primaries, Sanders now believes he has the momentum.
He says he believes the campaign for the Democratic nomination is headed for a contested convention, despite those who say the numbers don't add up.
"I think we got a real shot to win this. I think we have the momentum. I think we have the energy," said Sanders. "And I think we have the ideas that are resonating across this country."
In an interview before his rally, Sanders told Action News he is not concerned the Clinton campaign now plans to press him hard on the issues to stop his momentum.
"I am not intimidated by them at all. I guess they are getting nervous," said Sanders. "They're getting nervous because they are sensing that the American people are not supportive of a candidate who receives millions of dollars from Wall Street."
He says he believes his message is resonating, particularly among young people, because he advocates for things they believe in - like making tuition free for public colleges and universities.
When asked who will foot the bill, Sanders responded, "We pay for that through a tax on Wall Street speculation. And it's not free college. It's free tuition at public colleges and universities."
His supporters point to a number of reasons why they support Sanders over Hillary Clinton.
"I am African American, and I feel like Bernie is more for the community than Hillary really is," said Madeline Smich of Pittsgrove, New Jersey.
"I think Bernie Sanders stands for women's rights better than Hillary does, which is saying a lot because Hillary is a woman," said Amy Lattarm of West Chester, Pennsylvania.