[atmavatar]

Alas, several states still lack minimum ages, so your 30-on-12-year-old scenario is still quite possible in the US.

Particularly disturbing is how much pushback there was to the recent Oklahoma bill to finally end child marriage two weeks ago. Thankfully it passed anyway, but the state house vote was 51-36. Some of the quotes from the house members voting against the law are rather chilling, e.g.:

    “This was a vote in favor of parents rights over government overreach. It’s possible that some people are comfortable with the government overriding parental decisions, but I’m not one of them. To vote yes on this is a vote to let the government dictate how to parent your children.”
    - Rep. Clay Staires (R-Skiatook)

Prior to that, it was one of the aforementioned states without a minimum marriage age (in the case of pregnancies), so it was semi-common for families to force girls to marry the much older men who'd impregnated them.

AFAIK, California, Mississippi, and New Mexico still lack a minimum age for marriage.