A rare winter storm churned across the U.S. Gulf Coast on Tuesday, breaking snowfall records more than a century old in a southern region where flurries are unusual, as much of the United States remained in a dangerous deep freeze.

A snowstorm warning was in effect for 31 million people - from southern Texas east through Georgia and north to the Carolinas and into Virginia - until Wednesday morning, the National Weather Service said.

A major winter storm prompts blizzard warnings, dumping heavy snow and sleet in a region where even flurries are a rare sight.