Former president George H W Bush paid respects to his wife with his daughter as her body lies in repose before her funeral.
The 93-year-old was not due to attend the public viewing of Barbara Bush but he joined around 2,500 mourners on Friday, spending time shaking their hands during a 15-minute visit.
Family spokesman Jim McGrath said: "I think he was very touched by all of the people who were taking the time out of their lives."
Mrs Bush was the wife of the 41st president and the mother of the 43rd, one of only two first ladies to be able to make such a claim.
She drew many fans of her own with her work on literacy and AIDS awareness.
Her coffin was held in repose for 12 hours until midnight on Friday, until her funeral on Saturday, which will be at Mr Bush Sr's presidential library at Texas A&M University.
She will be buried at a gated plot next to their three-year-old daughter who died of leukemia in 1953.
Mrs Bush chose her son Jeb, former Florida governor, to deliver her eulogy along with her long-term friend Susan Baker, who is the wife of former Secretary of State James A Baker III.
Her husband's biographer Jon Meacham will also be involved in the eulogy.
More from US
Around 1,500 guests are expected to attend, including Melania Trump, Bill and Hillary Clinton, and Michelle and Barack Obama.
President Donald Trump is not attending out of respect for the family, the White House said, and because of concerns about additional security.