[astrodust]

You could do it on a state-by-state basis, where each may provide a differing level of coverage but all of them would provide at least a base-line care for citizens that are residents of that state.

This could lead to a form of "competition" where some states might provide perks to help encourage people to migrate there from other parts of the country or make it more attractive for prospective employers.

This is the way it's done in Canada. Each province has differing rules as to what's covered, but emergency treatment and preventative care is never impaired by cost or a lack of insurance.