He declared Nov. 6 "Dignity Day," urging everyone to skip work, knock on doors and help neighbors get to the polls.
"If necessary, we'll take a sick day on Nov. 6. Because if we lose, we're going to be sick on Nov. 7," he said, spurring laughter and cheers. "Nov. 6 is sick prevention day. Nov. 6 is our national health care plan."
The event, organized by the grassroots Democratic group Fight For Philly, drew about 300 people. Some came for the free food and some for the great weather, but most were excited to see Jackson.
Geraldine Roberson, 58, followed the reverend around with a camera, taking snapshots as he answered reporters' questions and posed for photos with fans.
"He did so much for us. So much," she gushed. "I'm about to cry. I just can't believe it, I've never seen him this close before."
The rally organizers initially intended to focus on voter ID. But with the law's implementation delayed until after Nov. 6, Jackson took the opportunity to discuss other concerns - gun control, racial disparities in the unemployment rate, and poverty, which he said are being ignored this election cycle.
"They had the debate in Denver, Colo.," he said, referring to the Oct. 3 match between President Obama and Republican nominee Mitt Romney. "And the moderator never mentioned Aurora, Colo., where people were killed and massacred with semiautomatic weapons."
He was similarly disappointed with the vice presidential debate in Kentucky. "You gonna have a debate in Appalachia, the poorest congressional district in the country, and not mention poverty?"
That message hit home with many in the audience.
"Like he said, everybody's talking about the middle class, upper class," said Sheila Rhames, 49. "But nobody's talking about the poor, poverty and our struggles."
"I'm a single person, why do I have to have a child and be married to be part of the middle class?" Rhames said, referring to spousal and parental tax breaks for which she doesn't qualify.
"The issue of poverty, I think that's getting left out of this election," said Emily Turner, a Penn law student who lives a few blocks from the park. She was out walking with her husband and daughter when they stumbled upon the rally.
"What's your No. 1 issue right now?" Turner asked her 9-year-old daughter Ana, a near-clone of her mom with thick red hair, knee-high socks and sneakers.
"People with no money," said Ana. She didn't know who Jackson was at first, but she knew about the civil rights movement and her mother helped connect the dots.
Jackson criticized states that have tried to pass voter-ID laws and purged registrations of inactive voters. He also slammed Pennsylvania for not allowing early voting. "You're only allowed to vote one day in this state. And it's an inconvenient day: Tuesday."
Alicia Cox, 30, and Najee Bah Larry, 21, were energized after hearing Jackson and others speak.
"I feel like I just left a big concert or something!" Cox said. The two women attend Bible Way Baptist Church near 52nd and Girard streets, one of five congregations Jackson visited Sunday morning.
They lamented that these types of rallies spring up only during election season.
"If they had more events like this, more people would be used to the positivity and be away from drugs and be more aware about who they voting for," said Bah Larry, who canvassed for Obama in 2008, before she was old enough to vote.On Saturday night, Jackson spoke at a Coalition of Black Trade Unionists panel on racial disparities in the unemployment rate.
"In the major cities like Philadelphia, unemployment among black males may be as high as 50 percent," he said in an interview Sunday, adding that such figures are evidence of "a kind of ethnic cleansing" that also shows up in high school dropout rates, foreclosure rates and efforts to eliminate race as a factor in college admissions.
Contact Jessica Parks at 215-854-4851 or firstname.lastname@example.org.