The need for family is what's driving Get on the Bus, a program that enables children to visit their mothers in California state prisons.

For some prisoners, "to be separated from their families is very painful," said Mercy Sister Carmel Crimmins, coordinator of the program for the Diocese of San Bernardino, where she is director of social and community services.

Staying connected to families is important for prisoners, she said, "because no visits, no calls militates against a good transition back into the community, the society."

Sister Louise Bond, Catholic chaplain at the California Institution for Women in Corona, said that through Get on the Bus many women are seeing "their children for the first time since they were incarcerated."

One prisoner last year "hadn't seen her daughter in 16 years," said Sister Bond, a member of the Sisters of the Holy Names of Jesus and Mary.

The two religious talked about Get on the Bus --- which takes place close to Mother's Day and this year was held May 12 --- in e-mail and phone interviews with Catholic News Service.

Sister Carmel said it was "the plight of families" that got the San Bernardino Diocese involved in the program five years ago. The Corona facility, which holds more than 2,000 inmates, is the only state prison for women in the diocese.

"However, many women from San Bernardino are incarcerated in Chowchilla, six and one-half hours' journey from here," she said. "These are the women we try to help by bringing their children to see them." In Chowchilla, Valley State Prison and the Central California Women's Facility house more than 7,400 women, with 75 percent of them mothers, according to a Get on the Bus press release.

The program is sponsored in San Bernardino by the Sisters of St. Joseph Ministerial Services with support from local volunteers, donors, faith communities and nonprofit organizations.

This year, 31 buses from cities around the state took more than 600 children, along with their guardians --- many of them the children's grandmothers --- and volunteers, to visit their mothers in five state prisons. Poverty and distance, with many of the prisons located far from urban centers, prevent more frequent visits, the nuns said.

Four of those buses originated in the San Bernardino Diocese, and 11 originated in the Archdiocese of Los Angeles, with numerous parishes and schools donating time and resources to help sponsor the effort. The cost of each bus is $4,000 and includes transportation expenses and meals for the trip. Also, the children are given t-shirts are photographed with their mothers, and on the way home they're given teddy bears and letters from their moms.

The response "has been phenomenal," Sister Carmel said. "Parishioners, Catholic associations and religious communities have been very generous with donations."

Volunteers accompany children on the buses and perform behind-the-scenes work. "It's a cast of thousands," said St. Joseph of Carondelet Sister Suzanne Jabro, executive director of Women and Criminal Justice, which coordinates the overall program.

The program grows each year to try and meet the need. "A lot of children are still emerging who haven't seen their mothers in years," added Sister Jabro. "They can't get [to a prison] unless they have the help of the community." This June for the first time, Get on the Bus will coordinate three buses of children to visit their fathers in prison near Father's Day.

Sister Carmel said the May 12 event helped the community to better understand the extent of the suffering and separation young people and their parents experience. She has heard comments like: "I knew women went to prison but I never thought of the children," "I never knew that women were sent so far away," and "It never dawned on me how impossible it would be to visit on public transportation."

"The vast majority (of the women) are not in prison for violent crimes but for addictions and money problems, such as bad checks and embezzlement," said Sister Carmel. "An awful lot don't need punishment, but need treatment," she said.

Sister Bond, who called the program "a great gift," said the prisoners "who have to be away from their children are often stressed and having the opportunity for a visit brings a lot of joy and hope for the future."

Among the prisoners, Junier De Young, 33, said, "It feels great to see how beautiful my girls are turning out." Maria Gastelum, 37, described the visit as "the best thing that's ever happened to me in a long time." Yolanda Hall, 35, said, "It feels just like heaven. This is a day to remember."

The children were also upbeat. Monique Gastelum, 19, said she was "overwhelmed with excitement.... This is one of the happiest days I've had in about four years." Chris Pasquotto, 14, said, "I got to see my mom today and I adore her. There is no one in the world I have like my mom."

But 8-year-old Carlie Villegas sounded a more subdued note. "It breaks my heart to see my mom cry," the child said.

---Ellie Hidalgo contributed to this article.