Insulators were originally designed to keep the wires linking telegraphs and telephones insulated from the wooden poles that held them aloft. In conjunction with the expansion of rural electrification in the early 20th century, there was a major boom in the manufacturing of insulators, with production peaking from the 1920s through the 1940s, when millions of Hemingray, Dominion, and Brookfield insulators were produced every year. Commonly...Continue Reading