Former first lady Barbara Bush gives her husband a kiss on the cheek. His wife of 73 year preceded him in death. (AP Photo)

Former President George H.W. Bush, left, strapped to Sgt. 1st Class Mike Elliott, a retired member of the Army's Golden Knights parachute team, land on the lawn at St. Anne's Episcopal Church after making a tandem parachute jump near Bush's summer home in Kennebunkport, Maine, Thursday, June 12, 2014. Bush made the jump, his eighth, in celebration of his 90th birthday. (AP Photo/Robert F. Bukaty)

FILE - In this May 29, 2014 file photo Harvard University President Drew Faust, left, speaks with former President George H. W. Bush, right, before Harvard commencement ceremonies in Cambridge, Mass. Bush was presented with an honorary doctor of laws degree during the ceremonies. President Faust, who was the first woman to lead Harvard University, announced Wednesday, June 14, 2017, that she will leave her post after the upcoming academic year saying in a letter "it will be the right time for the transition to Harvard's next chapter, led by a new president." (AP Photo/Steven Senne, File)

Former President George H.W. Bush waits on the field for first pitch ceremony before Game 5 of baseball's World Series against the Los Angeles Dodgers Sunday, Oct. 29, 2017, in Houston. (AP Photo/David J. Phillip)

Former president George H.W. Bush arrives for an NFL football game between the Houston Texans and the Indianapolis Colts, Sunday, Nov. 5, 2017, in Houston. (AP Photo/Eric Christian Smith)

Former President George H.W. Bush and wife, Barbara arrive on the field before the NFL Super Bowl 51 football game between the New England Patriots and the Atlanta Falcons, Sunday, Feb. 5, 2017, in Houston. (AP Photo/Charlie Riedel)

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. (AP Photo/David J. Phillip)