If you want to apply for top 50, IELTS 7 is MUST. (Even for some schools, 7 is not enough; ex: Georgetown/OSU-->7.5, Boston U requested hard 7, which means every section has to be 7)
In R1, I used IELTS to apply for MSU, UW, UCI and Emory; but my IELTS score is 7.