But that friendship was cut short when Knapp died of lung cancer in 2002.
Gail Caldwell wrote about their bond in the book "Let's Take the Long Way Home: A Memoir of Friendship," recently released in paperback.
Gail Galdwell in 2010 told Here & Now's Robin Young that writing about her friendship with Knapp was like trying to "capture air" because their relationship was about the "blissful routine of ordinary life."
"We walked, we talked, we talked about the dogs, we walked the dogs. We went home and called each other on the phone and walked some more," she said.
This segment originally aired in 2010
This segment aired on August 17, 2011.