#VisaCoach Video on Visiting USA for Marriage on non-immigrant visa
A foreigner who is already in the U.S. is welcome to marry a U.S. citizen or other person while here. Marriage procedures are set by the state and local governments, and not involved with immigration which is a Federal issue. For example two Canadians fly to Las Vegas, get married, return to Canada. Immigration is not involved. And the marriage is valid worldwide.
I personally did about the same thing. I was living in Hong Kong and engaged to Joyce. I had been an expat (American living outside the USA) for about 15 years by then. My friends and family were scattered all over the world. We decided to get married in Las Vegas, cause flights, food, and rooms in Las Vegas were bargain priced especially 20 years ago, and it would be easy for my family and friends to meet us there for our celebration.