"If I had cancer," said Dorwart, "I wouldn't say 'Oh, please don't tell.' "
Around 7 p.m., supporters and participants - many of whom walked in teams - gathered at the Art Museum steps for the opening ceremony.
Teammates clung to one another and wiped away tears as some honored lost loved ones by placing "honor beads" around luminaires on the stage.
James Holleran placed his beads for his daughter Madison, a University of Pennsylvania freshman who committed suicide in January.
The 49 people who walked for "Team Madison Strong" had raised more than $59,000, the highest team total.
Other teams included "Ruck Up," a group walking with weighted rucksacks for veterans who have died by suicide.
Their circuitous route meandered through Fairmount Park, South Philadelphia, and University City.
At 30th and Chestnut Streets, walkers passed the Finding the Light Within mural, which depicts the faces of many locals who have lost their lives to suicide. They were to return to the Art Museum for a closing ceremony at 5 a.m. Sunday.
To participate, each walker raised $1,000. The money helps fund programs such as "mental health first aid" training. It also goes toward survivor support groups and family bereavement efforts, said state regional director Patricia Gainey.
More than 1,500 people commit suicide each year in Pennsylvania, according to the Centers for Disease Control and Prevntion.
In Philadelphia, that number is about 180, said Arthur Evans, commissioner of the Department of Behavioral Health.
His crew works to reduce suicides through initiatives such as the "I Will Listen" campaign to fight the stigma surrounding mental illness.
One reason the foundation chose Philadelphia for this year's event is its large community of mental health crusaders, Gebbia said.
Melissa Hopely, 26, is one of them. The Havertown native works for Minding Your Mind, a group of speakers who visit schools to educate students about mental health. As a teen, she said, she was once moments away from suicide when a friend bounded into her bedroom.
Hopely and other speakers not only encourage kids to take care of their own mental health but also educate them about spotting signs of mental illness in others.
"You need to start really early," Hopely said. "Who says what age you start getting depressed?"
"How are all these people around me and no one knew what we're doing?" Dorwart recalled thinking after Vanessa's death. "I want this in schools."
"We teach kids 'stop, drop, and roll,' and 'just say no to drugs,' " said Cathy Siciliano, board chair of the Philadelphia chapter of AFSP. We should also teach them how to recognize and help friends in trouble, she said.
Some schools are leery about bringing up the topic, Hopely said. But each year, more welcome the program.
Suicide awareness has also gained political traction.
Gov. Corbett signed a bill Wednesday that requires public school teachers to undergo suicide-awareness training every five years.
And in Washington, Rep. Tim Murphy (R., Pa.) introduced a bill aimed at fixing what he called the country's "broken" mental health system, that would increase funding for suicide-prevention programs.
Some criticize the bill because it would allow parents to send children to an inpatient facility without the child's consent. But Murphy said the bill is needed to help parents get children help before they pose a danger.
"A person who is seriously mentally ill doesn't even recognize they have an illness," Murphy said.
Gebbia said that 90 percent of suicides involve mental disorders.
Through the efforts of the overnight walks and shorter community walks, AFSP hopes to reduce the number of suicides nationwide by 20 percent by 2025.
Dorwart said she has attended between 15 and 20 walks. She enjoys reuniting with friends who supported her, and supporting those more recently affected by suicide.
"Every year, there's a new family," Dorwart said. "It smacks you in the face every time."
Hopely wrote a book, The People You Meet in Real Life, in which she shares her own story, and the stories of others such as Vanessa Dorwart. If she sells 5,000 copies, Hopely will create a scholarship in honor of Vanessa and two other local kids who committed suicide.
People have asked Dorwart if her daughter died for a greater purpose. The question gives her pause.
"I don't know, but it won't be for nothing," Dorwart said. "It'll be for something. . . . I will not let her memory die."
BY THE NUMBERS
reported deaths by suicide in the U.S. in 2010
in Pa. in 2010
Percentage of people who die by suicide who have a mental disorder
SOURCES: CDC, American Foundation for Suicide Prevention