Los Angeles (CNN) -- The season of Father's Day and Mother's Day may be the loneliest for kids with a parent in prison.
So every May and June, a California nonprofit devoted to improving the criminal justice system takes busloads of youngsters to visit mom or dad behind bars.
Nancy Nunez, a 20-something mother of a toddler, is serving her time for carjacking in a state prison in Corona.
While she was overjoyed to see her child for Mother's Day last month, Nunez said she's learned that nothing can come from bad decisions.
"You miss out on a lot of opportunities," she said. "Especially being with your family."
The journeys, including several scheduled for Father's Day over three Saturdays beginning this weekend, are more than just a philanthropic, emotional reunion of divided families, according to the organizers of the Get on the Bus program, based in North Hollywood.
One of 11 children in California has a parent in prison, jail or on parole or probation, the group said. That amounts to about 856,000 children -- 297,000 of whom have a mom or dad in state prison or local jail, the organization said.
The agency contends that regular visits between kids and their imprisoned parent can lower rates of recidivism for the parent, the group said. Also, a child's chance of becoming delinquent increases dramatically when he's denied a visit with mom or dad in jail or prison, the group said.
But travel is a problem. About 60% of moms and dads in state prison are more than 100 miles from their kids, the nonprofit agency said.
So the group started offering free bus rides 12 years ago.
The organization was founded by Susan Jabro, a nun with the Sisters of St. Joseph, and it once operated under the non-profit auspices of the Roman Catholic Archdiocese of Los Angeles. But the agency is now an independent organization with partnerships with several universities and faiths, a program director said.
The agency say it's filling a void in the justice system because police and courts don't regularly inquire at the time of arrest or sentencing whether the suspect or convict has a child, the agency said. One out of five kids with parents in the criminal justice system has witnessed their parent's arrest, the group said.
The separation can change lives for the worse.
To help salve those wounds, about 150 children were bused to the state prison in Corona for Mother's Day last month. The kids hailed from throughout California: San Diego, Sacramento, the San Fernando Valley, south Los Angeles and San Bernardino.
"At Get on the Bus, we feel that children have a right to see, touch and talk with their parents no matter where they are," said program director Hilary Carson.
"There is promising research showing that children who visit their incarcerated parents are better socially and emotionally adjusted and they tend to break the cycle of intergenerational incarceration," Carson said.
"The idea of prisons can be scary for children, and that's where the most important people in their lives live," Carson added. "It's the worst punishment, if you can imagine to be separated from your child."
For Mother's Day, Get on the Bus provided free transportation for kids and their caregivers, travel bags for the children, comfort care bags for the caregivers, and a photograph of each child with his or her mother.
The children are fed breakfast, snacks on the bus, lunch at the prison, and dinner on the way home. After a four-hour visit at the prison, each child receives a teddy bear with a letter from their parent, as well as post-event counseling, organizers said.
Children with mothers in prison are usually cared for by relatives, often grandparents, who are unable to make the drive due to distance or expense. Some of the kids were accompanied by one of the program's 1,200 volunteers.
But to see mom, the youths had to experience a security check and walk past barbed wire and wary guards at the California Institution for Women in Corona.
The reunions prompted tears and elation. Moms and children often wept.
One boy serenaded his mother with a Bruno Mars song.
Nunez signed the cast on her son's broken arm with "Mom will always love you."
Another mom read a book to her child.
Photographs were also taken, with one photo to be given to the child and another to the incarcerated mom.
Martha Camasca said she was behind bars for aggravated assault.
She said if she could change things, she wouldn't have committed her crime.
The distance from her family, she said, just isn't worth it.
Many of the incarcerated mothers were serving time for non-violent or drug-related offenses in far away communities, amounting to a several hours' drive. Some hadn't seen their kids since being locked up, the moms said.
Nunez said she felt happy and sad at once because, as she put it, "The only thing I will have left when the day is over are the memories."