Question: What is the Legal Definition of Rape?

I was wondering if there is a source (or sources) for evaluating what is considered rape in each of the U.S. states. I want to know how it's defined by each state. If it is possible, I would also be interested in any information on the charges against those who are accused of rape. In other words, how do they differ from state to state? Recently in an online discussion forum, these questions were raised after someone brought up the "Men Can Stop Rape" posters. Many people were wondering how rape is defined legally in their respective states and how those definitions differ from state to state. Thank you very much!!