Andrea Spillars, deputy director and general counsel for the Missouri Department of Public Safety, urged survivors to check in.
Officials said previously they believe people who are unaccounted for aren't necessarily dead or trapped in debris. They say many are probably safe and but failed to tell friends and family where they are. Cell phone service in Joplin remains spotty.
The death toll in Joplin rose to 126 people, and officials have estimated more than 900 were injured.
More powerful storms swept through middle America, injuring dozens and tearing apart homes in Indiana, Illinois, Missouri and other states Wednesday night.
The weather service canceled tornado watches and warnings issued for most of Mississippi, northwestern Alabama and central Kentucky on Thursday. Forecasters said the heavy weather that blighted the Midwest in recent days has finally receded. Nevertheless, violent storms could not be ruled out elsewhere.
Forecasters said the Appalachians, parts of the Southeastern U.S., and the upper Ohio Valley into the northeastern U.S. remained at risk.
Powerful winds overturned two mobile homes in southern Indiana. Crews worked overnight to clear uprooted trees and downed power lines after a tornado touched down in a rural area near Bedford. Even with the extensive damage, residents expressed relief that no deaths were reported in the latest round of storms.
In Illinois, strong winds, rain and at least four possible tornadoes knocked down power lines and damaged at least one home and a number of farm buildings across the central and eastern parts of the state.
Wednesday's storms followed a deadly outbreak of violent weather a day earlier in Arkansas, Oklahoma and Kansas that killed at least 15 people.
The National Weather Service says there have been about 1,000 tornadoes so far this year. The death toll attributed to those twisters stands at more than 500.
Find out how you can donate to the relief efforts to help the victims of the massive tornadoes, including the ones that struck Joplin, Mo.
The Associated Press contributed to this story