Pronunciation: Oregon

I need some backup. At my place of work we call people all over the country, and a caller was speaking with a prospect from Oregon. After the call, we had a heated debate as to how to pronounce the name of this state. Other callers joined in, and we never arrived at a definitive conclusion.

[oʊrɪgɪn] [oʊrɪgan] [oʊrɪgən]

Which one is it?