Check out “A Chip Off the Old Sock” by Linzee over on the Etsy Blog Storque for the historical background on sock monkeys, their perennial fascination to collectors, and why crafters find them an amusing challenge to create.
The raw material for sock monkeys are Rockford Red Heels, socks that are currently made in Osage, Iowa, by Fox River Mills. The socks first appeared in 1932, when the Nelson Knitting Mills of Rockford, Illinois, added the red heels to differentiate their socks from those made by competitors. They named the heel the De-Tec-Tip. In 1951, when the company learned that crafters were turning De-Tec-Tip socks into stuffed animals, they started enclosing sock monkey instructions with each pair sold. Fox River continued the tradition (the pattern also includes instructions for a sock elephant) when it bought the assets of Nelson Knitting in 1992.