Although grades are very important decision when an American graduate school reviews a student's application, it is never the most important aspect. American schools almost always prioritize real work experience and research over getting good test scores. This is because they are seeking students who will be able to build up from the work that the student has done previously in order to advance his/her career.
That being said, graduates schools seeks potential students who have worked, done interships, participated in research, and volunteered with community service for at least 3 years. Oftentimes, the students who apply right after undergraduate school and who also are admitted to the school is because they have done significant work or research during their college time.
Hope this helps ^_^ |