Update: Sandy Strengthens; Thousands Evacuate; Wall Street Closes

Hurricane Sandy, the monster storm bearing down on the U.S. East Coast, strengthened on Monday after hundreds of thousands moved to higher ground, public transport shut down and the U.S. stock market suffered its first weather-related closure in 27 years. About 50 million people from the Mid-Atlantic to Canada were in the path of the nearly 1,000-mile-wide (1,600-km-wide) storm, which forecasters said could be the largest to hit the mainland in U.S. history. It was expected to topple trees, damage buildings, cause power outages and trigger heavy flooding.