Minimum requirement for TOEFL scores
Below is list of Universities and recommended TOEFL scores. Some departments/colleges might be flexible and don't use them as hard cut-off scores (if your overall profile is really good). Universities might still accept your application.
MIT IBT: 90 minimum; 100 recommended
MIT Graduate Mechanical Engineering TOEFL - 100 IBT
MIT Graduate EECS TOEFL Min. 100,
MIT graduate Economics TOEFL Min. 100
Stanford Graduate Economics - iBT 100
Stanford Business School - TOEFL iBT 100
As per EE department : if your TOEFL is lower than min. requirement you can still apply, if you are admitted you might have to take English courses.
Graduate school - TOEFL 87 (iBT)
Undergraduate school - TOEFL 100 (iBT)
EE - Graduate program - TOEFL iBT - 87
UT - Austin
TOEFL - 79 (School of Information)
Graduate School- TOEFL - 79
School of Journalism - TOEFL Min. 79 , Preferred 85, Average 105.
Mechanical Engg. (graduate program), Min. TOEFL is 79.
Undergraduate admissions - TOEFL iBT -100.
School of Arts - Min. TOEFL 100 (iBT)
Graduate (CS) - 101
Graduate (law school)- Min. TOEFL 105 (iBT)
University of Florida
Warrington School of Business: TOEFL - 80 (iBT)
Department of Computer & Information Science & Engineering - TOEFL 80 (iBT)
Undergraduate- TOEFL 85
Graduate- TOEFL : 80
Graduate ECE -TOEFL : 90
TOEFL iBT - 79
College of Nursing/Pharmacy - TOEFL 100
Graduate school TOEFL 80
Carey School of Business - TOEFL :80
School of Molecular Sciences - TOEFL : 100
Engineering(graduate) - TOEFL : 80
Iowa State University
Undergraduate - TOEFL :71 (iBT)
Graduate - TOEFL :81 (iBT)
Graduate - Mechanical Engineering : 79 (iBT)
Please note: if you have a very good profile and if your TOEFL score is lower than minimum requirement, there is still a chance. You might get conditional admission (you might have to take English classes etc). Since all courses are taught in English a good understanding of English is really important. If you are planning to study in USA, it's highly recommended to schedule your TOEFL exam in advance and prepare well for TOEFL (make sure you get a good score in ETS prep software before appearing for the actual Test).
TOEFL is required from non native English speakers. If you are non native speaker but you have completed your last degree in countries like UK, Canada, US, Australia, New Zealand your TOEFL requirement might be waived.