The National Association of REALTORS® was founded as the National Association of Real Estate Exchanges on May 12, 1908 in Chicago. With 120 founding members, 19 Boards, and one state association, the National Association of Real Estate Exchanges' objective was "to unite the real estate men of America for the purpose of effectively exerting a combined influence upon matters affecting real estate interests."

The Association's founding boards included the Baltimore; Bellingham, Wash.; Chicago; Cincinnati; Cleveland; Detroit; Duluth, Minn.; Gary, Ind.; Kansas City, Mo.; Los Angeles; Milwaukee; Minneapolis; Omaha, Neb.; Philadelphia; St. Louis; St. Paul, Minn.; Seattle; Sioux City, Iowa; and Tacoma, Wash., boards and the California State Realty Federation (now the California Association of REALTORS®).

The Code of Ethics was adopted in 1913 with the Golden Rule as its theme.

In 1916, the National Association of Real Estate Exchange's name was changed to The National Association of Real Estate Boards (NAREB). That same year, the term “REALTORS®,” identifying real estate professionals who are members of the National Association and subscribers to its strict Code of Ethics, was devised by Charles N. Chadbourn, a past president of the Minneapolis Real Estate Board.

The collective marks REALTORS® and REALTORS® were registered with the United States Patent and Trademark Office on Sept. 13, 1949, and Jan. 10, 1950, respectively, under Registration Numbers 515,200 and 519,789. Since then, the association has maintained a vigilant defense of the trademarks, prevailing in numerous cases. Most recently, in Zimmerman v. NAR (2004), the Trademark Trial and Appeal Board denied a request to cancel the trademarks.

In 1972, the name of the National Association of Real Estate Boards was changed to the National Association of REALTORS® (NAR). The block "R" logo was adopted by the Association in 1973.

The Association became the largest trade association in the United States in the early 1970s, with over 400,000 members. Today, the National Association of REALTORS® has over 1.1 million members, 54 state associations (including Guam, Puerto Rico, and the Virgin Islands) and more than 1,300 local associations.

(source: https://www.nar.realtor/)