Suspect the dress code might vary depending where in the states you are as well as the vibe of the couple. I don't know for certain, but reckon that a NY cocktail wedding may be different to Los Angeles.
Also, depends how big the wedding is and how much you care TBH. An enormous wedding, I'd just wear it and have done. Make sure to get nails and may be hair done before, and dress pressed, because that is much more prevalent in the US regardless of location.