[2][3][4][5] About 60 percent of AFT's membership works directly in education, with the remainder of the union's members composed of paraprofessionals and school-related personnel; local, state and federal employees; higher education faculty and staff, and nurses and other healthcare professionals.

By 1919, AFT had 100 local affiliates and a membership of approximately 11,000 teachers, which amounted to 1.5% of the nation's teaching force.

In its early days, AFT distinguished itself from the National Education Association (NEA) by its exclusion of school administrators from membership.

Facing opposition from politicians and boards of education, membership in AFT declined to 7,000 by 1930.

During the 1930s, AFT, whose members had historically been primary school teachers, saw influential college professors join the union.

[10] For 27 years, Shanker wrote a weekly column entitled "Where We Stand" that ran as an advertisement in The New York Times.

[14] On February 12, 2008, McElroy announced he would retire at the union's regularly scheduled biennial convention in July.

[17] Since 1980, AFT and the NEA have contributed nearly $57.4 million to federal campaigns, an amount that is about 30 percent higher than any single corporation or other union.

The plaintiffs argued that unions were violating their constitutional right to free speech by forcing them to either support union-favored causes and candidates or lose access to important job benefits such as disability and life insurance.

[25] In 2018, the landmark Supreme Court ruling in Janus v. AFSCME resolved this matter, concluding that public sector union fees violate the First Amendment, compelling nonmembers to "subsidize private speech on matters of substantial public concern".

[28] It filed an amicus brief in the 1954 U.S. Supreme Court desegregation case Brown v. Board of Education.

[8] By the late 1940s, AFT was slowly moving toward collective bargaining as an official policy.

[30] In 2010, four American film documentaries, most notably Waiting for Superman, portrayed the AFT as hurting children by opposing charter schools and protecting incompetent teachers.