Polygamy...right, wrong, or culturally defined?

Polygamy is an issue that many Christians, and even non-Christians, would say is wrong. It is even illegal to have multiple wives in America. Why is this? Is it a law that was set in place because the forefathers thought it was Biblical, or was it a cultural norm? This is a question that was raised during my cultural anthropology class. I have done a lot of thinking and reading on this subject and I have finally come to a conclusion...polygamy is culturally significant. Let me say that again, polygamy is NOT wrong. Now, you cant quote me all the scripture you want but unless we are talking about a leader of a church, in which case they are to have only one spouse, there is nothing in the Bible that says polygamy is wrong. This view is supported by an entire missions organization in Africa. We recently had a missions conference at my church and a woman who ministers to Gambia agreed with my view. So now that you know my opinion, what is yours? Let me know what you think on the subject and your thoughts on my views. Please comment!