Nothing could be further from the truth. The cover letter supplements the resume. It focuses attention on your achievements and gets a prospective employer interested in you.
Cover letters are especially important to new graduates.
Through the cover letter, you can persuade an employer to look past a possibly thin work history to see the value of your education and non-professional experience. Always supply a cover letter with your resume - even if one isn't specifically requested. You may also include how you came to hear about this opportunity. Make a stronger impression by limiting your focus to one or two experiences. Dear Ms. Williams, I would like to apply for the position of Junior Analyst, as posted in the career bulletin at Boston University.