SAN DIEGO - Joan B. Kroc, the billionaire widow of McDonald's Corp. founder Ray Kroc who became known as North Dakota's "angel" for her $15 million contribution to state flood recovery efforts, has died of brain cancer.

Kroc died Sunday at age 75.

"Her gift gave our people hope, because there were a lot of people who didn't have any dollars," said Pat Owens, the former mayor of Grand Forks, N.D. "They were out of their homes, and they had no money for food, no place to stay."

Grand Forks and neighboring East Grand Forks, Minn., were overrun by the flooding Red River in April 1997. Almost 60,000 people were evacuated from the two cities. Shortly after the river overwhelmed sandbag dikes that protected Grand Forks, a fire destroyed much of the city's downtown.

Kroc later told Owens she saw her on television - wearing a pair of jeans Owens said were too small - and said to herself, "I'm going to help that little fox."

"I never forgot that," Owens said Sunday in an interview from Ocala, Fla. "I thought that was really kind of comical."

Kroc donated $15 million to the flood victims, with the stipulation that it be distributed as $2,000 checks for families who had lived within a mandatory evacuation area.

Kroc insisted her gift be anonymous, and Owens referred to Kroc only as the "angel." Kroc's identity became known when she visited the flooded communities.

Eliot Glassheim, a Grand Forks city councilman and state legislator, called the donation "breathtaking."

"It was a very important factor in making us feel that somebody cared about the city," Glassheim said. "An awful lot of people were just buoyed up by it."

Owens and Kroc kept in touch afterward by phone and letter. "Everything she did was very generous," Owens said. "She had a generous heart."

Kroc was known in recent years as a major donor to organizations working to promote world peace, including namesake think tanks at the University of Notre Dame and the University of San Diego.

She inherited the San Diego Padres after her husband died in 1984 and sold the baseball club in 1990 to a group led by Los Angeles television producer Tom Werner.

Kroc died at her home in the San Diego suburb of Rancho Santa Fe, several months after being diagnosed with glioblastoma, a form of brain cancer, said Dick Starmann, her spokesman.

With an estimated net worth of $1.7 billion, Kroc ranked No. 121 on Forbes magazine's latest list of the nation's wealthiest people. Her donations created Notre Dame's Joan B. Kroc Institute for International Peace Studies in 1986 and the University of San Diego's Joan B. Kroc Institute for Peace and Justice in 2001. She was also a major benefactor of the Carter Center of Emory University in Atlanta.

Kroc contributed $12 million to establish the Notre Dame center after hearing the Rev. Theodore M. Hesburgh, then president of the university, warn about the arms race at a San Diego talk in 1985, said Scott Appleby, the center's director.

"She walked up to him after the talk and said, 'I'm going to help you,"' said Appleby. "She was a passionate champion of peace and justice and she was single-minded in her dedication to eliminating the threat of nuclear weapons and all forms of deadly violence."

The University of San Diego think tank has worked to broker peace in hot spots including Nepal, Madagascar and the Ivory Coast, said Joyce Neu, executive director, who pegged Kroc's donations to the center at more than $30 million.

Kroc also contributed more than $90 million to the Salvation Army for a 12.5-acre arts and recreation center in east San Diego, said Maj. Cindy Foley, the center's administrator.

"She worried that there were children and families who didn't have an opportunity to discover their talents because of a lack of facilities," Maj. Foley said. "She embodied the word generosity."

Born Aug. 27, 1928 in St. Paul, Minn., Kroc was a musician and music teacher for many years. She married Ray Kroc in 1969 and the couple moved from Chicago to San Diego in 1976, two years after purchasing the Padres and preventing the team's planned move to Washington, D.C.

When Ray Kroc died in 1984 at age 81, his wife succeeded him as the Padres' owner and chairwoman. She admitted knowing nothing about baseball when she took the helm, but that did not stop her from speaking out. The Padres went to the World Series in her first season, losing to the Detroit Tigers.

Kroc was deeply involved in running the team, at one point rehiring Manager Dick Williams after he was fired without her consultation. She sold the team in 1990, not because of the team's poor performance, she said, but because she wanted to spend more time with her family.

"I'm a few years older now, and, unlike Zsa Zsa (Gabor), I'm not ashamed to admit that I'll be 62 next August," she said in a 1989 interview. "I think it's time to prioritize."

Kroc is survived by a daughter, four granddaughters and four great-grandchildren.

Joan Beverly Mansfield Kroc