Employers who list positions are busy with a significant number of students applying. It is simply not enough to apply online and wait for an employer to contact you. It is recommended you follow up with each employer who receives your resume.
As a rule, if you have not received a response to your application within 10 business days, post deadline date, you should follow-up with an email or call. Most managers appreciate a follow-up call as it shows a sincere and continued interest in their company. If you really want the job and you think you have a chance, call up to two or three times total. If the manager doesn't seem interested, it is best to move on.