The town is about 75 miles southwest of Chicago.
About 200 homes in Marseilles are a total loss and many more have severe damage.
Wednesday, much of Marseilles resembles a scrapyard: piles of debris are taller than people and homes are literally a shell of their former selves.
"I raised my daughters in this house and my grandkids," said flood victim Erin Henry.
Erin and Lloyd Henry were among the 1,500 people evacuated, about a third of the town.
"I have structural damage in my concrete and my walls," said Lloyd Henry. "So I think me and my wife lost everything that we own."
The water from the Illinois River was a rushing torrent, powerful enough to sweep away homes' foundations and closing the town's only school indefinitely.
"It's heart-wrenching to see so many things I saw this morning, with the tennis shoes floating in different areas and stuff," said Marseilles Elementary School Superintendent JoEllen Fuller.
"This flood was not a backwater-type flooding," said Marseilles Police Chief Jim Hovious. "There was a very strong current."
Sisters Kay and Maureen Harvey are both in their 70s and live with their mother, who is 100 years old.
Are they prepared to start over?
"Not at 70," said Maureen Harvey. "I should be enjoying it and kicking my shoes off and saying, OK, I'm done for today."
The Harveys live a couple hundred yards from Marseilles dam, now the scene of a major recovery operation.
The dam was damaged by several barges that broke free. The Coast Guard is now investigating whether that incident made the flooding worse.
Salvage operations on the remaining six barges floating or submerged near the Marseilles Dam is still going on. On Tuesday, three tug boats removed the first submerged barge from the water near the dam.
"They are beginning some recovery with the barges," said Chief Hovious. "Where they're at, it's ongoing. It's a challenge."
Many of Marseilles' 4,100 residents say, in the past, they've only seen basement flooding, not the 6-8 feet of water that's flooding the first floor of many buildings.