I think you did misunderstand. Those laws are the province of State and local Govts, not Federal. The commonly accepted rule is 3 inch or less in most places. Alaska is rather exceptional being less populated than most. In the lower 48 the majority have settled on some rather arbitrary regulations. When I say here I generally mean my home State or my locality and say in the US when I mean nationally. Got into that habit on IRC where the users are very much spread over the globe.