No bidder found for 'Peanuts' letters
Sotheby's had estimated that the letters would sell for $250,000 to $350,000 at Friday's sale.
The cartoonist wrote the affectionate letters to a young woman in 1970-1971.
The 44 letters included 22 original drawings of some of the comic strip's characters, including Charlie Brown, Snoopy and Lucy.
Sotheby's called it the most significant collection of correspondence and drawings by Schulz to come to auction.
Schulz died in 2000 at age 77.
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