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Romantic letters and drawings the late Peanuts creator Charles Schulz were sent to a young woman 23 years his junior. (Sotheby's/Associated Press)

A rare archive of letters and drawings by Peanuts creator Charles Schulz did not find a buyer at a New York City auction.

Sotheby's had estimated that the letters would sell for $250,000 to $350,000 US 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.