The National Weather Service said freezing rain is possible Wednesday in Texas and Arkansas. An inch or two of snow was forecast in parts of Oklahoma on Wednesday.
In Texas, authorities said at least six people died in weather-related traffic accidents and three immigrants died of hypothermia.
Roads, bridges and overpasses were slick and hazardous. The treacherous mix of sleet and freezing rain made ghost towns of some Dallas-Fort Worth suburbs, reports CBS News Correspondent Bob McNamara. Travel became risky business, when traffic was moving at all.
A motorist stranded in Arkansas and two people who had stopped to help were killed Tuesday when a vehicle driven by state Rep. Johnnie Bolin went over a slick spot and plowed into them on a median of Interstate 530 near Redfield.
Bolin was hospitalized but not badly hurt. Police said no charges were being considered.
In Tulsa, Okla., Larry Carlin shoveled snow, hoping to prevent the 8 inches of snow already on the ground from freezing hard under the snow expected to fall Wednesday.
"The last time I remember it being this cold this long was way back in the 1970s," said Carlin, 60, who has lived in Tulsa for 26 years. "When we first moved here, about three years passed before it snowed. And even then, our daughter had to gather snow from four yards to build a snowman."
Some freezing rain started to fall late Tuesday night in southwest Arkansas, and the weather service issued a winter weather advisory for almost the entire state.
Freezing drizzle was also expected Wednesday morning in parts of Texas, and many schools were to remain closed for a second day Wednesday.
On Tuesday, ice in north and central Texas sent cars spinning and grounded planes. A series of collisions snarled traffic on Interstate 20 near Dallas; several 18-wheelers were jackknifed, said Department of Public Safety Sr. Cpl. Robert White.
"As soon as they clear one collision, another was happening," he said.
In Arkansas, some motorists were trapped in their vehicles for 10 hours on slippery Interstate 40 after a truck jackknifed outside Little Rock. Truck drivers walked down the highway knocking on car windows to make sure everyone was all right.
"My stomach was growling because I hadn't eaten anything," said motorist Renee Lewis. "That man went back to his cab. He brought us chips, cupcakes, baked chicken and rice. I cannot believe somebody took the time to do that."
Though the storm had been predicted since last week, highway sanding crews couldn't keep ahead of it. Scores of school districts, government offices and businesses were closed Tuesday.
Wrecks and slippery pavement also closed roads in parts of Oklahoma, Arkansas, Tennessee, Mississippi and Alabama; schools were closed in parts of all six states.
"I'm sick of winter. I'm going to go kill the groundhog," said Carla Gaster, with Nashville's Boy Scouts of America Service Center.
Oklahoma officials closed some roads indefinitely because they were coated with snow and ice. The National Guard, patrolling the roads in Humvees, carried two dozen stranded motorists to a Red Cross shelter.
The National Weather Service said another round of light snow and freezing rain and ice would pass through Oklahoma and Arkansas early Wednesday, then move through the Ohio Valley to the mid-Atlantic states.
The heaviest snowfall Tuesday was 13 inches at Mount Ida, Ark., in the Ouachita Mountains. Up to 8 inches of snow fell overnight in southeastern Oklahoma.
In Southern California, snow fell at elevations as low as 4,500 feet after a Pacific storm moved east from the Los Angeles Basin. A motorist whose pickup truck skidded off the Pasadena Freeway and plunged into a waterway was rescued by a Los Angeles fire helicopter crew in the early morning darkness.