The Chicago-based company is choosing a location to build its new 400-seat 777X jetliner.
The state submitted an offer yesterday that would provide economic incentives if Boeing selects Illinois.
David Roeder is a spokesman for the Illinois Department of Commerce. He says it's "a compelling proposal" but that he couldn't elaborate because of a confidentiality agreement.
Boeing is looking at a $7 billion to $10 billion plant that would start with 3,250 workers in 2018 and grow to 8,500 by 2024.
Several other states also submitted offers by yesterday's deadline. They include Missouri, Alabama and California.
Boeing officials are expected to announce the new plant's location early next year.