For more than a century, the Boy Scouts of America and the Mormon church formed an ideal pair as they helped each other expand their organizations and build their brands while molding countless young men through bow knots, pinewood derby races and campouts.

But as the calendar flipped to the 21st Century, the longtime partners originally drawn to each other by shared values began drifting apart. The Mormon church continued expanding into far off countries where Boy Scouts wasn't offered and began eyeing its own program. Amid declining membership, Boy Scouts of America recently opened its arms to openly gay youth members and adult volunteers, transgender boys, and girls while the Mormon religion clung to its opposition of homosexuality and stuck to its traditional gender roles.

On Tuesday, the two sides announced what had become inevitable: They will split permanently starting in 2020.

The memories will live on in Norman Rockwell paintings, the Boy Scouts training complex named after a former Mormon church president and in the pictures from the church's 2013 extravagant theatrical production commemorating their 100th anniversary together.

But, their futures are now headed in divergent directions.

The Boy Scouts will try to make up for the loss of its largest sponsor through the addition of girls and a welcoming message that all are invited. Last week, the organization said it will change the name of its flagship program next year to Scouts BSA to account for the inclusion of girls.

The organization says its current youth participation is about 2.3 million, down from 2.6 million in 2013 and more than 4 million in peak years of the past. So far, nearly 4,000 girls have joined roughly 170 Cub Scout packs participating in the first phase of the new policy, and the pace is expected to intensify this summer under a nationwide multimedia recruitment campaign.

The Church of Jesus Christ of Latter-day Saints will bank on nurturing its youth in a still-to-be developed program set to launch in 2020 that will likely include outdoor activities and character building similar to Boy Scouts but be tailored for the church's doctrine and designed to roll out around the globe.

Unhitching from Boy Scouts will trigger nostalgia for American Mormons who grew up aiming for the important life milestone of Eagle Scout, said Mormon scholar Patrick Mason, professor of religion at Claremont Graduate University in California. Mason, who is Mormon, said his mother told him and his three brothers they couldn't get their driver's license until they earned Eagle Scout.

Joining the Boy Scouts is practically automatic among Mormon boys, and the religion has long been the biggest sponsor of Boy Scout troops in the United States. The 425,000 Mormon boys who will be leaving represent about 18.5 percent of youth in the Boy Scouts. Another 185,000 Mormon boys ages of 14 and 18 already left the Boy Scouts this year to focus on church-related activities and community service.

Mason said the time had clearly come for a split — with the Boy Scouts following shifting American culture that no longer matched church's core principles. The Mormon church, which opposes gay marriage and considers homosexual relationships a sin, initially said it was "deeply troubled" by the Boy Scouts' 2015 policy change on gays but stayed after receiving assurances it could appoint troop leaders according to its own religious values.

"The church remains concerned about cultural drift. The church doesn't want to move with the culture. So actually this is kind of a counter-cultural move," Mason said.

The move also shows the Utah-based religion's efforts to solidify its global footprint. More than half of the church's 16 million members live outside the U.S.

"The great challenge that Mormonism is facing right now is if it can make that leap from being simply a religion that is present all around the world and become a religion that is rooted all around the world," said Matthew Bowman, a Mormon scholar and associate professor of history at Henderson State University in Arkadelphia, Arkansas.

The church's announcement also revealed that its existing program for girls will be shuttered and replaced by the new youth program, leading Mason and Bowman to predict that more parity could be in store for girls and boys even while the church stops short of allowing women in the lay priesthood.

The church has long spent more money on Boy Scouts than the internal girls program and given more recognition to boys who earn Eagle Scout than girls who earn the highest medallion in their program, they said.

The new program will also give the Mormons a shot at putting young members on a path closely tethered to the church that can then lead to a mission, and hopefully, lifelong membership, Mason said.

"It's great to get the boys out in canoes and shooting bows and arrows but that's not going to do them any long term good if they leave the church," Mason said. "The focus is going to be on faith because they're worried about the rising tide of secularization."

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Associated Press national writer David Crary contributed to this report from New York.