The chair that birthed Harry Potter and millions of Potterheads is hitting the auction block. The wooden dining chair once owned by JK Rowling, comes with a letter in which she said she was sad to let it go.

It was used by Rowling while she wrote the first two Harry Potter books – Harry Potter And The Philosopher's Stone and Harry Potter And The Chamber Of Secrets. James Gannon, director of rare books at Heritage Auctions, said: "This is a chair that JK Rowling wrote the first two Harry Potter books on. And it was in her government flat. It was given to her with a group of chairs. And this was the most comfortable so she used it to write the first two – she says in her letter that she parked it in front of her typewriter and it stayed there."

Gannon admits the chair itself isn't that valuable, but when you tie in Harry Potter it instantly becomes historic. "She said at the time that it's something you would pick up at a junk shop. But it's really just the fact that she took the time to decorate it and the fact that she actually wrote the books in it is important. But the fact that she took the time to decorate it and sign it say 'I wrote Harry Potter in this chair,' I think is very important."

The chair and the letter were first auction off by Rowling in 2002 at the Chair-ish a Child auction, which benefited the National Society for the Prevention of Cruelty to Children sold for over $23,000 (£16,200) It was sold again in 2009 fetching $29,000. Heritage Auctions started biding at $45,000 and it currently stands at $65,000.

"There's not that many things in the Harry Potter world that are especially valuable because her books became so popular so fast. And then they were published in huge editions. So they're not that uncommon," Gannon admitted.

The auction also includes a lot of seven British first editions of the Harry Potter series all signed by the author, with a starting bid of $10,000-10,500. The Dallas, Texas based auction house will also sell a 1776 broadside printing of the Declaration of Independence which is expected to bring in over $160,000. The Colony's copy belonged to an Ipswich pastor. The live auction will be held at New York City's Waldorf Astoria hotel and online at on 6 April.