Over 1500 universities in US accept IELTS scores these days. 1500 universities is only about 30 percent of total universities in United States, hence just 30 percent universities in US recognize IELTS till this date. There are many reputed universities in USA which don't accept any other English proficiency test except TOEFL. All the universities in US which accept IELTS also accept TOEFL but all the universities in US which accept TOEFL don't accept IELTS.

Universities with IELTS recognition in US:
http://qna.educouncil.org/Universities_and_Colleges/nZxyNXyyXyN.html

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