Hardest hit was Alabama where 61 people died, most when a mile-wide tornado gouged its way across the state.
Storms also killed 11 in Mississippi, four in Georgia and one in Tennessee
In Tuscaloosa, where at least 15 people were killed, some neighborhoods were reduced to rubble and drivers abandoned cars in streets littered with downed trees and power lines.
"What we faced today was massive damage on a scale we have not seen in Tuscaloosa in quite some time," said Walter Maddox, mayor of the 83,000 population town.
One hospital emergency room took in 100 people.
A Birmingham family was trapped briefly in their home by uprooted trees.
"As I was grabbing my daughter and running to the closet, they hit the house," said Lisa Hey, who estimated 90% of the trees in her neighborhood were toppled.
"Teams have pre-deployed to begin debris removal and search and rescue operations as soon as conditions permit," said Alabama emergency agency spokeswoman Lauree Ashcom in a statement.
The monster twisters forced three nuclear reactors in Alabama to shut, leaving about 245,000 households and businesses in Alabama without power.
A Louisiana police officer was killed at a campsite in Choctaw County, Miss., when a tree fell onto his tent as he used his body to shield his 9-year-old daughter, said Kim Korthuis, a supervisor with the National Park Service.
"She wasn't hurt, just scared and soaking wet," said Greg Maier, a campsite volunteer.
Much of northern Texas, including areas recently charred by wildfires, also was pounded by tornadoes and severe thunderstorms.
"Numerous homes have been damaged or destroyed," said Lt. Chuck Allen, emergency management coordinator in Van Zandt County, located about halfway between Dallas and Tyler.
This week's storms have added to the violent weather that has pummeled much of the south this month.
Two weeks ago, at least 47 people died as storms tore a wide path from Oklahoma to North Carolina.
The latest wild weather - a nearly 600 mile stretch - began in the Midwest plains, moved through the south and Wednesday night was headed as far north as Pennsylvania and upstate New York.
The National Weather Service said as many as 21 states could be hit by severe weather before things clear up Friday.
About 74 tornadoes were reported Wednesday along with hundreds of reports of wind and hail damage.
Roads were washed out or blocked by fallen trees and power lines, houses, schools and businesses were flattened, flooded or set on fire by lightning and wind-whipped debris became deadly flying projectiles throughout the four-state hot zone.
Hundreds of people were evacuated from their homes in Missouri after levees failed to hold back swollen rivers.
"I'm just glad my family is safe," said Chris Pigg, who spent the night at a shelter with his wife and daughter and wasn't sure if he'd have a home to return to after the Black River breached the levee in Poplar Bluff.
Governors called out the National Guard to help with rescue and cleanup operations, and states of emergency were declared in Alabama, Arkansas, Kentucky, Mississippi, Missouri, Tennessee and Oklahoma.
