Worldwide, depending on the country, vaccination is mandatory, mandatory just for school entry or recommended. (1)
In countries where the vaccination is not mandatory, it is important to realise the deadly consequences measles can have if a child is not vaccinated, and how infectious measles is.
CDC state that a child can get measles just by being in a room where a person with measles has been, even after two hours the person have had left.  You can get measles in any country you are due to risk of getting infected while travelling (you or others around you). (2)