Teams with the Federal Emergency Management Agency (FEMA) will begin assessing tornado damage in Illinois on Thursday.
Governor Pat Quinn’s office says the assessments are necessary so the state can request federal assistance.
Five teams will look at damage to homes and businesses in Champaign, Grundy, Massac, Pope, Tazewell and Will counties.
Sunday’s tornadoes destroyed hundreds of homes and left six people dead in Illinois.
Quinn has declared disaster areas in 13 counties.
The National Weather Service has confirmed 55 tornadoes touched down across 12 states, 16 of those twisters hit in Illinois.
The biggest tornado hit the town of Washington, Illinois and left a 46 mile long path of destruction. Officials say winds from the tornado were at its peak of 190 mph when it struck the town and it grew to one half-mile wide.
Washington Mayor Gary Manier estimates that the EF4 tornado damaged or destroyed about 1,000 homes in the town.
One person was killed by that twister.
Residents have been allowed to return to their homes to salvage personal belongings during restricted homes. Police are trying to prevent looting.