AUSTIN, Texas (AP) — Lady Bird Johnson, the former first lady who championed conservation and worked tenaciously for the political career of her husband, former President Lyndon B. Johnson, died Wednesday, a family spokeswoman said. She was 94.

She died at her Austin home of natural causes about 4:20 p.m. Elizabeth Christian, the spokeswoman, said she was surrounded by family and friends.

Lady Bird Johnson returned home late last month after a week at Seton Medical Center, where she’d been admitted for a low-grade fever.

She was hospitalized with a stroke in 2002 that made speaking difficult. But even after that she continued to make public appearances and in May attended an event at the LBJ Library and Museum featuring historian Robert Dallek.

In March, she listened from Texas through a conference call when President Bush signed legislation naming the Education Department headquarters building in Washington, D.C., after her late husband.

The longest-living first lady in history was Bess Truman, who was 97 when she died in 1982.

Born Claudia Alta Taylor, the daughter of a Texas rancher, Mrs. Johnson spent 34 years in Washington while her husband held the offices of congressional secretary, U.S. representative, senator, vice president and president.

President Johnson died in 1973, just four years after leaving the office he assumed after John F. Kennedy’s assassination in Dallas in November 1963. Faced with growing civil unrest and challenges from within his own Democratic Party over his Vietnam War policies, President Johnson declined to seek re-election in 1968.

The couple had two daughters, Lynda Bird, born in 1944, and Luci Baines, born in 1947. The couple returned to Texas after the presidency, and Mrs. Johnson lived for more than 30 years in and near Austin.

“I think we all love seeing those we love loved well, and Austin has loved my mother very well. This community has been so caring,” Luci Baines Johnson said in an interview with The Associated Press in December 2001.

“People often ask me about walking in her shadow, following in the footsteps of somebody like Lady Bird Johnson,” she said. “My mother made her own unique imprint on this land.”

Former President George H.W. Bush said she exemplified “the grace and the elegance and the decency and sincerity that you would hope for in the White House.”

As first lady, she was perhaps best known as the determined environmentalist who wanted roadside billboards and junkyards replaced with trees and wildflowers. She raised hundreds of thousands of dollars to beautify Washington. The $320 million Highway Beautification Bill, passed in 1965, was known as “The Lady Bird Bill,” and she made speeches and lobbied Congress to win its passage.

“Had it not been for her, I think that the whole subject of the environment might not have been introduced to the public stage in just the way it was and just the time it was,” Harry Middleton, retired director of the LBJ Library and Museum, once said.

Mrs. Johnson once turned down a class valedictorian’s medal because of her fear of public speaking, but she joined in every one of her husband’s campaigns. She was soft-spoken but rarely lost her composure, despite heckling and grueling campaign schedules. She once appeared for 47 speeches in four days.

“How Lady Bird can do all the things she does without ever stubbing her toe, I’ll just never know, because I sure stub mine sometimes,” her husband once said.