Gallery: Former Presidents George H.W. Bush and George W. Bush accompanied by their family members watch as pallbearers carry the casket of former first lady Barbara Bush after a funeral service Bush at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: The hearse carrying former first lady Barbara Bush passes through members of the Texas A&M Corps of Cadets as it nears her husband's presidential library at the university on Saturday, April 21, 2018, in College Station, Texas. After an invitation-only funeral in Houston, Bush, who died on Tuesday, was buried at a gated plot near the library as 700 members of the Corps of Cadets lined the Barbara Bush Drive leading up to the library.

Gallery: People line up on the top of a parking garage to pay tribute as they wait for the motorcade carrying former first lady Barbara Bush on George Bush Drive, Saturday, April 21, 2018, in College Station, Texas.

Gallery: Former President George W. Bush and his father former President George H.W. Bush watch as the casket of former first lady Barbara Bush is loaded into a hearse at St. Martin's Episcopal church, Saturday, April 21, 2018, in Houston. (AP Photo/Evan Vucci)

Gallery: Pallbearers carry the casket of former first lady Barbara Bush after a funeral service for former first lady Barbara Bush at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: Former Florida Gov. Jeb Bush places his hand on the casket of his mother, former first lady Barbara Bush during a funeral service at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: The casket of former first lady Barbara Bush is moved after a funeral service at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: Former Florida Governor Jeb Bush comforts his father, former President George H.W. Bush during a funeral service for his mother, former first lady Barbara Bush at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: Former Florida Governor Jeb Bush speaks during a funeral service for his mother, former first lady Barbara Bush at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: Former President George H. W. Bush is comforted by his daughter Dorothy "Doro" Bush Koch during a funeral service for former first lady Barbara Bush at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: Jon Meacham speaks during a funeral service for former first lady Barbara Bush at St. Martin's Episcopal Church, Saturday, April 21, 2018, in Houston.

Gallery: The casket is brought into St. Martin's Episcopal Church during the funeral for former first lady Barbara Bush on Saturday, April 21, 2018, in Houston.

Gallery: Former Presidents George W. Bush, left, and George H.W. Bush arrive at St. Martin's Episcopal Church for a funeral service for former first lady Barbara Bush, Saturday, April 21, 2018, in Houston.

Gallery: First Lady Melania Trump arrives at St. Martin's Episcopal Church for a funeral service for former first lady Barbara Bush, Saturday, April 21, 2018, in Houston.

Gallery: Accompanied by his wife, Hillary Clinton,left, former President Bill Clinton arrives at St. Martin's Episcopal Church for a funeral service for former first lady Barbara Bush, Saturday, April 21, 2018, in Houston.

Gallery: Former President Barack Obama and former first lady Michelle Obama greet first lady Melania Trump at St. Martin's Episcopal Church for a funeral service for former first lady Barbara Bush, Saturday, April 21, 2018, in Houston.

Gallery: Karl Rove arrives at St. Martin's Episcopal Church for a funeral service for former first lady Barbara Bush, Saturday, April 21, 2018, in Houston.

Gallery: Billy Bush arrives at St. Martin's Episcopal Church for a funeral service for former first lady Barbara Bush, Saturday, April 21, 2018, in Houston.

Gallery: Mourners gather at St. Martin's Episcopal Church during a funeral service for former first lady Barbara Bush, Saturday, April 21, 2018, in Houston.

Gallery: Former U.S. President George H. W. Bush looks at the coffin of his late wife, former first lady Barbara Bush, with his daughter Dorothy "Doro" Bush Koch at St. Martin's Episcopal Church in Houston, April 20, 2018. (Mark Burns/Office of George H.W. Bush/Pool via The New York Times) -- FOR EDITORIAL USE ONLY. --