A / AE Inside the 1%-a-year floodplain: about a 26% chance of flooding over a 30-year mortgage. AE has a mapped base flood elevation; plain A does not.
Floodway The channel and the land beside it that has to be kept clear enough to carry the flood. Building here is tightly limited.
X shaded The 0.2% (500-year) floodplain, plus some levee-protected and very shallow flood areas.
X Outside both lines. No federal requirement to insure, which is not the same as no risk.
If a building is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
The average NFIP premium across Illinois was $1,072 a year on August 31, 2026 (premium plus the federal policy fee; the reserve fund assessment and HFIAA surcharge come on top). Risk Rating 2.0 prices each building on its own flood risk, so a quote can be far from the average.
Outside the high-risk zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Quotes: FloodSmart.gov or a local agent.