Jack Hall and Sam both survive the storm. Jack finds Sam in the library, they get rescued by some government helicopters and are flown back to Mexico. Laura Chapman also survives. Most of the people in the Northern States / Canada / Northern Europe die during the storm (including all the people who leave the library during the storm to walk south). The US president also dies. The rest flock down to Mexico which only allowed the Americans in because they nullified all the Latin American debt.