Sinead O'Connor, who was reported missing after failing to return from a bike ride, has been found "safe".
Police launched an appeal on Monday to trace the 49-year-old Irish singer, who had not been seen since she left at 6am on Sunday in the Chicago suburb of Wilmette.
A police spokesman said: "She was found safe and is no longer listed as missing or in danger."
The gifted but troubled singer-songwriter is known as much for her fierce and expressive voice as her shaved head and blunt criticism of the Catholic Church and other institutions.
Paradigm Talent Agency, which represents O'Connor, declined to comment about her apparent disappearance.
O'Connor was sued this month by comedian Arsenio Hall over a Facebook post that stated investigators looking into the supplier of drugs used by Prince should question Hall. She also accused him of drugging her.
In November, she posted a message on Facebook saying she had taken an overdose at a hotel somewhere in Ireland. Irish police later said she had been found safe. The next month, O'Connor posted on Facebook that she had been detained in a hospital for mental health evaluation.
Her rendition of Nothing Compares 2 U topped charts from Europe to Australia, and earned O'Connor multiple Grammy Award nominations. In 1991, O'Connor was named artist of the year by Rolling Stone.
But her blunt-spoken manner often drew criticism, especially in the United States.
In 1990, some US radio stations refused to play her music after she banned the Star-Spangled Banner from her show in New Jersey.
An outspoken critic of the Roman Catholic Church over the way it handled sexual abuse by clergy, she drew intense criticism in 1992 when she ripped up a picture of Pope John Paul II on Saturday Night Live.
Over the years O'Connor has voiced support for other young female performers facing intense public scrutiny, including Britney Spears and Miley Cyrus.
O'Connor, who was diagnosed with bipolar disorder more than a decade ago, has spoken of her mental health problems. She told Oprah Winfrey in 2007 that before her diagnosis she had struggled with thoughts of suicide and overwhelming fear. She said at the time that medication had helped her find more balance, but "it's a work in progress".
In 2012, O'Connor cancelled a planned tour, saying her doctor had told her to rest after a "very serious breakdown".
O'Connor, who has been married four times and has four children, signed a deal in 2014 to write a memoir.