This is the youngest thread I could find to add to :). I don't know if a list is needed seeing as how laws can change but I made one anyway and thought I could share it. At least it's as of this writing.
In Canada, it's in the national criminal code to require a "responsible person keeping watch". I would like to go about trying to change that to allow a mirror. Having heard that different states have different rules, I investigated what they all have on their books. My list lists just the rules for public-water free-skiing. Several states relax some rules if you're in a tournament or using a recognized course. I'm not listing those specifics. The list will be state,[observer wording or age],[mirror],[flag];. Oh look...pretty much a csv. :) Use the semi as a line break...if that works. :)
State,Observer,Mirror,Flag;Alabama,12,yes,;Alaska,12,yes,;Arizona,12,,yes;Arkansas,12,yes,;California,12,,yes;Colorado,person,,yes;Connecticut,12,,;Delaware,competent person,,;DC,12,,;Florida,observer,yes,;Georgia,person,yes,;Hawaii,competent person,yes,;Idaho,competent person,,;Illinois,competent person,,;Indiana,person (Ohio riv 12),(Ohio riv yes),;Iowa,responsible person,,;Kansas,12,yes,yes;Kentucky,12,yes,;Louisiana,competent person,yes,;Maine,12,,;Maryland,12,,;Massachusetts,12,,;Michigan,person,,;Minnesota,person,yes,;Mississippi,10,,;Missouri,12,yes,;Montana,person,,;Nebraska,12,yes,;Nevada,12,,yes;New Hampshire,13,,;New Jersey,competent observer,,yes;New Mexico,,,yes;New York,10,,;North Carolina,observer,yes,;North Dakota,person,,;Ohio,10,,;Oklahoma,8,yes,;Oregon,observer,,yes;Pennsylvania,competent observer,,;Rhode Island,12,,;South Carolina,person,yes,;South Dakota,competent person,yes,;Tennessee,12,yes,;Texas,13,yes,;Utah,observer,,yes;Vermont,12,,;Virginia,observer,,;Washington,observer,,yes;West Virginia,12,yes,;Wisconsin,competent person,,;Wyoming,,,yes;
North Carolina appears to not need anything if the skier is wearing a "life preserver". Indiana seems to let more go on the Ohio River. Nevada has a little age thing depending on the age of the driver or something.