where did the phrase blue collar come from
Blue-collar worker The term blue collar was first used in reference to trades jobs in 1924, in an Alden, Iowa newspaper.[1]  The phrase stems from the image of manual workers wearing blue denim or chambray shirts as part of their uniforms.[2] Industrial and manual workers often wear durable canvas or cotton clothing that may be soiled during the course of their work. Navy and light blue colors conceal potential dirt or grease on the worker's clothing, helping him or her to appear cleaner. For the same reason, blue is a popular color for boilersuits which protect workers' clothing. Some blue collar workers have uniforms with the name of the business and/or the individual's name embroidered or printed on it.