The storm system that spawned deadly tornadoes in Texas brought heavy snow, ice and blustery winds to several states, as well as heavy rain in already waterlogged areas where flooding was blamed for more than a dozen deaths.
More than 2,800 flights across the US were cancelled on Monday - more than half of them at Chicago's two main airports - and around 4,800 were delayed, according to flight-tracking service FlightAware. A typical day sees about 150 cancellations and 4,000 delays.
At least 11 people died and dozens were injured in the tornadoes that swept through the Dallas area on Saturday. Snow from New Mexico through the Midwest, plus flooding in Arkansas, Missouri and Illinois, added to the succession of severe weather events in the last week that led to about four dozen deaths.
Highways turned icy and treacherous in New Mexico, while Oklahoma governor Mary Fallin declared a state of emergency after blizzard conditions affected parts of the state and heavy rain fell.
Oklahoma Highway Patrol said the body of a 22-year-old man was recovered in the north of the state but a second man, the lead singer of country-rock band Backroad Anthem, was still missing after the two went duck hunting and their boat capsized.
The body of a 36-year-old man who tried to cross a creek in his pick-up truck near the town of Arpelar was also recovered.
Officials in Arkansas said a 31-year-old man died in a storm-related drowning.
Several inches of rain caused flooding in Illinois and Missouri, where governor Jay Nixon also declared a state of emergency. Mr Nixon says the state's death toll from days of pounding rainfall had risen to 10, and he expected that number to grow.
The Mississippi River neared a potential record crest, after an unusual amount of late-autumn rain had the river already high before torrential downpours that began on Saturday.
Mississippi governor Phil Bryant said the state was seeking a national disaster declaration for some or all of the seven counties hit by a tornado last week and authorities in Georgia said they recovered the body of a man whose car was swept away when floodwaters overtook it.
Texas governor Greg Abbott made disaster declarations for four counties - Dallas, Collin, Rockwall and Ellis. Officials estimated as many as 1,450 homes in North Texas were damaged or destroyed by at least nine tornadoes.
The National Weather Service has said an EF-4 tornado, which is the second-most powerful with winds up to more than 200mph, hit Garland. Eight people died there, 15 were injured and more than 600 structures, mostly single-family homes, were damaged.
"I've never seen anything like this, with this scale of destruction," Garland police chief Mitch Bates said.
Authorities believe all eight of the tornado victims there, which included a one-year-old, died when their vehicles were thrown from flyovers in the Interstate 30 area and the George Bush Turnpike, a major route in the region.
With rain all day on Sunday keeping people away, Garland residents worked on a dreary and frigid Monday to salvage what they could, with the American Red Cross distributing items like tarpaulins, rakes and work gloves to help them.
Interstate 40, the main east-west highway across the Texas Panhandle, reopened on Monday morning. Most other roads across West Texas and the Panhandle had also reopened by the evening, although snow-packed roads and ice made driving hazardous.