1916, "real estate agent," American English, as though an agent noun from realty, coined by real estate agent Charles N. Chadbourn of Minneapolis, Minn., to distinguish the legitimate section of the business; popularized 1920s; patented as Realtor by the National Association of Real Estate Boards.
The 1916 Convention of the National Association of Real Estate Boards (NAREB) approved the adoption of the term as the official designation of an active member of the Association. In 1920 the District Court of Hennepin County, Minnesota, decided in favor of the Realtors in a case against a telephone directory publisher that had indiscriminately used the word in listings. The court asserted that the word "had never been used in any way whatsoever until so invented" and could thus be used only by those duly licensed by the National Association of Real Estate Boards. Until the Lanham Acts of 1948 changed federal patent regulations to allow protection for registered collective marks, the National Association fought and won sixteen cases on the local and state levels to protect its symbolic property. [Jeffrey M. Hornstein, "The Rise of Realtor," in "The Middling Sorts: Explorations in the History of the American Middle Class," New York, 2001]