Thermal earmuffs were invented in 1873 by American teenager Chester Greenwood, resident of Farmington in Maine in the United States, at 15 years of age, later receiving a patent for his improved invention in 1877, and by 1883 his company produced 30,000 a year and by 1936, 400,000 were being produced annually. In the patent document No.188,292, which he obtained four years later, the invention is described as “Improvement in Ear-Mufflers”.