The Nelson Knitting Co. of Rockford, Ill., may not have invented the sock monkey, but it standardized its manufacturing process somewhat. In 1932, the company added a line of socks whose red heels assured their customers that they were indeed purchasing original "Rockfords." When worn out, the socks were then deployed as playthings by American mothers who made stuffed monkeys out of them, using the red heel as a mouth. Hearing about these enterprising homemakers and seeing great promotional opportunity, the Nelson Knitting Co. began including a sock-monkey pattern with every pair of socks.