“So many of you have never seen an event like this,” Louisiana’s state climatologist warned, with New Orleans facing possibly the most snow it has ever seen.

Closures of schools, airports and businesses were taking effect in areas from southern Texas to Florida and South Carolina. Snow and ice could bring major travel disruptions and power outages.

The industry is pumping ever more oil and natural gas, but it is doing so with only about three-quarters as many workers as it employed a decade ago.

A winter storm was sweeping across a wide swath of the South on Friday. Atlanta’s airport issued a ground stop after a plane was evacuated onto a snowy runway.

Cargo could stop flowing at East and Gulf Coast ports, which handle most imports, if a union and an employers’ group can’t agree on the use of machines that can operate without humans.

Strong storms spawned tornadoes in Texas and Mississippi on Saturday and dumped heavy rain on the Carolinas on Sunday.