Mecham recalled a recent conversation she and their oldest son, former President and Texas Governor George W. Bush had. Theirs was the longest marriage of any presidential couple.
Barbara Bush was known as the "Enforcer" in her family, the glue who kept the high-powered clan together. "It would have been exactly what Barbara Bush wanted".
A program shows that Barbara Bush's granddaughters will offer a reading during the service and her grandsons will serve pallbearers. The scene would be repeated as eight of Bush's grandchildren carried her casket outside following the service.
The White House said in a statement that Trump will not attend the service "to avoid disruptions due to added security, and out of respect for the Bush Family and friends attending the service". Among the invited were first lady Melanie Trump, four former presidents, two former first ladies, Arizona Congresswoman Gabby Giffords and retired astronaut Mark Kelly.
Meacham wrote a 2015 biography of George H.W. Bush, who is attending the service along with many members of his family and three other former presidents. The church is adorned with sprays of yellow garden roses, yellow snap dragons, antique hydrangeas and other flowers.
They stopped along the way to shake hands, as mourners sang "Joyful, joyful, we adore thee", which Barbara Bush had requested as the final song.
Bush, only the second woman in U.S. history to have had a husband and son elected President, died Tuesday at the age of 92 at her home in Houston.
The American dynasty left on the 90-mile journey to the George H.W. Bush Presidential Library for a burial, and for the end of something more than a life.
Among the other roughly 1,500 guests were former Rep.
"She was the gold standard of what it meant to be a friend", said eulogist Susan Garrett Baker, wife of former secretary of state James Baker, who was George H.W. Bush's White House chief of staff. "My sincerest thoughts and prayers continue to be with George H.W., and the entire Bush family".
On Friday, more than 6,200 people visited the Houston church during a public viewing.
In another nod to the former first lady, many women wore pearl necklaces to the funeral, a clear acknowledgment of her signature accessory.
After seeing how many people had lined up to pay their respects to his wife, former President George H.W. Bush made a decision to attend - he sat at the front of the church in a wheelchair, offering his hand and smiled as people shook it, for about 15 minutes. From his wheelchair, he spent about 15 minutes shaking hands with people who had come.
When Barbara Bush lived in the White House, her husband called for a volunteer force of "a thousand points of light" to make America a "kinder, gentler nation".
About 1,500 people are expected at Saturday's private service, including four former presidents - Bush's husband and son, George H.W. and George W. Bush, Bill Clinton and Barack Obama.
Barbara Bush will be laid to rest in a gated plot at her husband's presidential library at the university in College Station, Texas. The couple's daughter Robin is also buried there. She died of leukemia in 1953.
Hundreds of people are lining both sides of the street near where the procession with turn to enter campus.
Guests arriving for the funeral for former first lady Barbara Bush are starting to fill the nation's largest Episcopal church, embracing and talking beneath the church's cavernous sanctuary.
Baker spoke wistfully about how Barbara Bush welcomed her family into the "Washington world" decades ago, hosting events for homeless people at the vice president's mansion "when that wasn't popular".