Professors in the United States commonly occupy any of several positions in academia. In the U.S., the word "professor" informally refers collectively to the academic ranks of assistant professor, associate professor, or professor. This usage differs from the predominant usage of the word professor internationally, where the unqualified word professor only refers to "full professors." The majority of university lecturers and instructors in the United States, as of 2015[update], do not occupy these tenure-track ranks, but are part-time adjuncts.
Research and education are among the main tasks of tenured and tenure-track professors, with the amount of time spent on research or teaching depending strongly on the type of institution. Publication of articles in conferences, journals, and books is essential to occupational advancement. As of August 2007, teaching in tertiary educational institutions is one of the fastest growing occupations, topping the U.S. Department of Labor's list of "above average wages and high projected growth occupations", with a projected increase of 524,000 positions between 2004 and 2014. In 2011, a survey conducted by TIAA-CREF Institute senior researcher Paul J. Yakoboski estimated that 73% of professors with senior tenure ranged between the ages of 60 and 66 and that the remaining 27% were above the age of 66. Yakoboski estimated that 75% of these professors have acknowledged that they have made no preparations for retirement due to the ongoing financial crisis and reluctance to leave their profession. A 2013 survey conducted by Fidelity Investments would echo similar results when the question about retirement came up.
In 2013, the National Center for Education Statistics counted 181,530 professors, 155,095 associate professors, 166,045 assistant professors, 99,304 instructors, 36,728 lecturers, and 152,689 other full-time faculty.
Salaries vary widely by field and rank, ranging from $45,927 for an assistant professor in theology to $136,634 for a full professor in legal professions and studies. A 2005 study by the College and University Professional Association for Human Resources found the average salary for all faculty members, including instructors, to be $66,407, placing half of all faculty members in the top 15.3% of income earners above the age of 25. Median salaries were $54,000 for assistant professors, $64,000 for associate professors and $86,000 for full professors 2005. During the 2005–2006 year, salaries for assistant professors ranged from $45,927 in theology to $81,005 in law. For associate professors, salaries ranged from $56,943 in theology to $98,530 in law, while salaries among full professors ranged from $68,214 in theology to $136,634 in law. During the 2010–2011 year, associate professor salaries vary from $59,593 in theology to $93,767 in law. Full professors at elite institutions commonly enjoy six-figure incomes, such as $123,300 at UCLA or $148,500 at Stanford. The CSU system, which is the largest system in the U.S., with over 11,000 faculty members, had an average full-time faculty salary of $74,000 in 2007, which had been scheduled to increase to $91,000 by 2011. Unfortunately for these faculty, the ensuing crash of the U.S. economy resulted in temporary pay reductions and total salary stagnation at the 2007 level instead, in spite of ongoing inflation. Professors in teacher education sometimes earn less than they would if they were still elementary classroom teachers. In one case study report, it was shown that a beginning full-time tenure-track assistant professor in elementary teacher education at California State University, Northridge was hired in 2002 at a salary of $53,000, which was $15,738 less than she would have earned in her previous position as a 9-month public school kindergarten teacher ($68,738).
Non-tenure track faculty make from $1,500 to $4,000 per course, so that if teaching four courses per semester – a schedule difficult to maintain for reasons of distance and market saturation, and a higher teaching load than tenure-track faculty usually endure – they can earn from $12,000 to $32,000 per year.
The following table uses figures for the 2005–2006 academic year: