It has to be approved by the U.S. Senate and Represenitives. then it has to get approved by the president. If the president veto's it, then the Senate and Represenatives can override it but that is a long system.
Dont take it for 100% fact but if you were on a railroad crossing and you couldnt see the track for 400 feet either way you would want to careful and watch the tracks and cross slowly.