Main question: The specific US legal statutes on forced marriage (would expect federal, yet not sure)?
Reading through Wikipedia, I was surprised to find that Forced Marriage only became illegal in the UK in 2014 and Canada in 2015 respectively. And the USA was not listed anywhere.
I then looked at: USA (forced marriage) and Sex Trafficking (forced marriage)(USA) expecting it to be listed, yet they only talked about sex trafficking, with "they're usually forced to get married."
The USA website on the topic is also rather vague. It doesn't point you at a law. Does not say "is blatantly federally illegal."
[emphasis mine] "The U.S. government is opposed to forced marriage and considers it to be a serious human rights abuse .... In some U.S. states, forced marriage is a crime, and in all U.S. states, people who force someone to marry may be charged with violating state laws, including those against domestic violence, child abuse, rape, assault, kidnapping, threats of violence, stalking, or coercion."
The State Department also mostly just says its a problem, "call us."
Question Reiteration: What is the actual US law on forced marriage? If no federal law, then at least general summary of the state landscape? (My Guesses: Always/mostly/sometimes outright illegal? Frowned upon? Only enforced relative to trafficking?)