At least four deaths were blamed on the storm.
The National Weather Service issued a winter storm warning, effective until 6 p.m. Friday. Schools canceled classes, airline flights remained grounded and shoppers in search of supplies jammed store aisles, KDFW-TV, Dallas, reported.
At least 160,000 people in North Texas had lost electricity by evening.
The low temperatures were predicted to remain for several days.
Treacherous ice threatened to create havoc from Texas to Tennessee in what was predicted to be the United States' "worst ice storm" in nearly five years.
Road conditions deteriorated through Thursday night and into Friday, and one person was killed on a highway in Arlington, Texas. Police said Chase Brandenburgh, 29, died when his car struck a stopped truck.
DART, Dallas' rapid transit system, suspended rail service, and commuters were warned to expect major delays in bus transport.
ONCOR, the North Texas electrical supplier, reported power outages in 250,000 homes.
Governors of Tennessee and Arkansas declared states of emergency and some schools in Oklahoma, Tennessee and Arkansas were closed, with the ice -- and snow -- storm threatening to coat everything in its path, officials said.
"The most unsettling aspect about Arkansas' weather for most of us is its looming uncertainty," Gov. Mike Beebe said.
In Memphis, organizers of the St. Jude Marathon decided early Friday evening to cancel this year's event, scheduled for Saturday, WFCW-TV reported.
"There are about 7,800 of our fellow Memphians already without power, and I didn't want to divert any resources from this great city away from those people that are people in need," Rick Shadyac, head of the marathon organization, said after surveying the route.
Tennessee, Memphis Light, Gas and Water was prepping for the worst in case "a significant storm blankets our city," President and Chief Executive Officer Jerry Collins Jr. said.
The utility has 426,000 customers.
Freezing rain and ice buildup hit metro areas from Dallas to Little Rock, Ark.; Cape Girardeau, Mo.; Memphis; Evansville, Ind.; and Louisville, Ky.
"This will be the worst ice storm for the United States since January 2009 and will affect many of the same areas as that storm," AccuWeather.com storm chaser Jesse Ferrell said.
The storm threat prompted Dallas officials to cancel the city's holiday parade -- a first in 26 years, CNN reported.
The Dallas Marathon, scheduled for Sunday, was canceled, organizers said.
The National Weather Service forecast the wintry mix would hang around until Sunday.
Besides the ice, a larger winter storm system powered by a huge arctic air blast was spreading snow and sleet from New Mexico to New York.
The Upper Midwest was trapped in the deep freeze with temperatures in some areas below zero and wind chills plunging the feels-like temps even lower.
In the early morning hours Friday, an NWS spotter reported as much as 7 inches of snow accumulation in Marissa, Ill., southeast of St. Louis, AccuWeather.com said.
The Illinois Transportation Department said early Friday most roads in southern Illinois were snow- or ice-covered, including Interstate-57 from the Tennessee state line north.
Highway officials in Texas reported snow covered Interstate-20 southwest of Fort Worth.
Police in Bradley, Texas, reported a solid sheet of ice on roadways.