Quinn has declared 38 Illinois counties state disaster areas after surveying flood damage from the heavy rainstorms across Illinois.
The disaster declaration, issued Thursday night, will speed and expand the deployment of state emergency resources. It also allows the state to seek federal help.
Flash floods and rivers that have quickly risen to record or near-record levels have inundated communities. Thousands of people have been evacuated around the state, and the floodwaters have damaged or destroyed homes and business and shut down roads.
In a statement announcing the disaster declaration, Quinn says "Illinois has seen an incredible level of devastation and reports indicate that conditions will get worse in the coming days."
Forecasters expect that many rivers won't crest until the weekend, raising the possibility of more flooding.
Counties included in the governor's declaration include: Adams, Brown, Bureau, Calhoun, Carroll, Cass, Champaign, Cook, DeKalb, DuPage, Fulton, Greene, Grundy, Hancock, Henderson, Henry, Jersey, Jo Daviess, Kane, Kendall, Lake, LaSalle, Marshall, Mason, McHenry, Mercer, Morgan, Peoria, Pike, Putnam, Rock Island, Schuyler, Scott, Tazewell, Whiteside, Will, Winnebago and Woodford.
The governor said his state disaster declaration begins the application process for federal aid.
"This is April 19th," Quinn said. "Thirty days from today, on May 19th, we'll have to file for any federal disaster relief."
The governor wants homeowners -- like Sheila Smith in Bellwood -- to help Illinois make its case for federal aid by carefully documenting their damages caused the flood.
"The water just kept coming and coming and coming and coming," Smith said.
In west suburban Hinsdale, U.S. Congressman Mike Quigley toured neighborhoods and promised to use his power to pressure officials in Washington to make Illinois eligible for federal disaster relief.
Chicago Mayor Rahm Emanuel, who left Chicago during Thursday's rainstorm for pre-scheduled meetings in Washington, returned to the city Friday afternoon for his first look at damage in the Albany Park neighborhood.
Governor Quinn canceled his schedule Thursday and immediately began touring areas downstate and the Chicago suburbs.
In Riverside and in Bellwood, neighbors appreciated Quinn's concern and promises to help:
"It's nice to know that you're noticed," said Riverside resident Josephine Lies-Doherty, "and that they see the pain that some of these people are going through."
The Associated Press contributed to this report.
