He was the first governor to appoint a black cabinet officer. Later in life, he worked on prison reform, and he recently lent his name to drives to reform the judiciary and rename the Department of Public Welfare.
"He defied labels and conventional thinking," Gov. Corbett said, noting Mr. Leader's support of civil rights and his warnings against budget deficits. Corbett called him a "central source of advice" for many officeholders, including himself, and ordered flags lowered to half-staff.
"He was cooking with gas five weeks ago," said former Gov. Ed Rendell. The two men worked together in March as part of a group of former governors backing a so-called merit selection system for choosing appellate judges.
Rendell sought Leader's endorsement in the 2002 Democratic primary race for governor when most top Democrats were backing Bob Casey, then auditor general and now a U.S. senator. Leader signed on - but only after a grilling, Rendell recalled.
"In typical George Leader fashion, he cross-examined me on every issue of the day," Rendell said.
Before politics, Mr. Leader was a farmer. After leaving office, he developed a string of 23 nursing homes.
He was a seventh-generation Pennsylvania Dutchman whose family had farmed in York County since colonial days. An ancestor fought in the Continental Army. His mother's family was Plain People and Dunkards who had migrated to south-central Pennsylvania seeking religious freedom.
His father perfected a breed of chicken - the Leader Leghorn - and was a staunch Democrat who served in the state Senate. "Democratic politics were everyday conversation at the Leaders' ever since I can remember," the son once said. "I grew into it naturally."
He attended a one-room school, completing the eight-year curriculum in six. He received a degree in education from the University of Pennsylvania in l939. But World War II cut short his postgraduate studies at Penn.
He served in the Pacific as an ensign and lieutenant in the Navy Reserve. But his father's health brought him back to help run the farm. In 1950 he was elected a state senator after illness forced his father to retire.
Mr. Leader later purchased a 28-acre hatchery then producing 100,000 chicks a year; by 1954, it was producing more than a million. He also ran an 89-acre cattle farm.
In his first statewide campaign, for treasurer in 1952, Mr. Leader lost amid Dwight D. Eisenhower's GOP presidential landslide. He managed to poll more than two million votes, however, and two years later he was nominated for the governorship.
He campaigned hard, accusing Republicans of "soak-the-poor" economic policies. His 1954 election was an upset.
In later years, he said he was the first real media candidate for governor, and won because he raised enough money for radio and television ads.
"I was an unknown candidate," he recalled. "I campaigned for eight months on street corners across the state, making up to 12 to 16 speeches a day. But it was computed that I reached only a quarter to a half-million people that way. On television, I could reach that many people in one shot on one big station. It was the television campaign that did it."
He was only the third Democrat to win the job since the Civil War - and the second-youngest governor ever. (The youngest was George Pattison, elected at 32 in 1882.)
In his inaugural speech, he spoke of economic prosperity but also of the need to "prevent injustice," "protect against oppression," and help the elderly and the mentally ill.
He launched what was then the nation's largest school-building program, boosted spending on public health and the needy, led an unprecedented highway building boom, and opened more state parks.
"He defined what it means to be a statesman," said Auditor General Eugene DePasquale, a fellow Democrat and York Countian. He said Mr. Leader introduced a professionalism to state government that still benefits officials today.
When DePasquale last saw him six months ago, he was struggling to walk but not to think. "Sharp as a tack," DePasquale said.
Barred by law from seeking reelection, he ran for U.S. Senate in 1958; many Democratic pols, angry at his cuts to the patronage system, sat on their hands. Republican Hugh Scott won.
In 1982, with an eye to retirement, Leader sold his nursing homes. Idleness was not for him, however. He formed Leader Family Corp. to develop a new type of personal-care home, tailored to elderly residents who need little help in their daily lives.
In recent years he seldom attended political dinners. "When I do give a speech," he quipped last year to an Inquirer reporter, "I say, 'I am here tonight to prove I am still alive.' "
But he remained concerned with how his state was run. He joined a bipartisan push to cut incarceration rates, including using drug and alcohol treatment as an alternative to jail for nonviolent offenders.
"Every idea has a time, and this is one for which the time has come," a white-haired Mr. Leader said last year. "The idea is to reform the prisons in a way that over the next five years is going to save the taxpayers a quarter of a billion dollars."
His wife of more than seven decades, the former Mary Jane Strickler, died in 2011. A son, Fred, died in 2003.
Mr. Leader is survived by a daughter, Jane Janeczek, sons David and George III; 12 grandchildren, and two great-grandchildren. Funeral arrangements were incomplete.
Contact Thomas Fitzgerald at 215-854-2718 or email@example.com, or follow @tomfitzgerald on Twitter.
This obituary was originally prepared by former Inquirer staff writer John Clancy.