The mayor of Boston ordered all vehicles offthe city's streets from 12 noon (1700 GMT) Friday as thenorth-eastern US braced for a blizzard, dpa reported. The storm was expected to form just off the southern coast ofMassachusetts when two weather systems - one approaching from the south and the other from the west - combine. The National Weather Service said Thursday a "major and potentially historic winter storm" was expected to impact an area encompassing all of New York State, most of the state of Pennsylvania and all of New England, Friday into Saturday. New England consists of the states of Maine, New Hampshire,Vermont, Massachusetts, Rhode Island, and Connecticut. Massachusetts capital Boston, with a population of 4.6 million inits metropolitan area, was expected to be the worst hit, with up to 60 centimetres of snow.