Louise was Andrew Carnegie’s most trusted confidant. “I can’t imagine myself without Lou’s guardianship,” he often said. He didn’t make one decision without first asking “Lou’s” opinion. In her quiet manner, she helped oversee one of the largest fortunes in US history, changing philanthropy forever.
Following her husband’s death in 1919, she retained the Hall for six years before selling it in 1925. Louise was an influential member of the board of the Carnegie Corporation of New York until her death in Manhattan on June 24, 1946, at the age of 89.