Park Forest's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Park Forest is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Park Forest in the 40th percentile nationally for seismic hazard - higher than 40% of the 4,875 US cities USGS was checked against here.

Where Park Forest sits in Illinois

The raw figures: peak ground acceleration 0.063g, short-period spectral response 0.126g, 1-second spectral response 0.068g. Among 330 Illinois cities in this dataset, Park Forest ranks 174 for seismic hazard, the 47th percentile within the state. About 21,016 people live in Park Forest, Illinois.

Bracing and bolting: the actual cost

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Illinois. A typical retrofit still runs $5,000-$10,000 nationally, about $7,000 for a common single-family job.

Insuring against this, not just retrofitting

Outside California, earthquake coverage is typically sold as an endorsement added to a standard homeowners policy, not a separate product - worth asking about directly when getting a home-insurance quote for a Park Forest address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Park Forest's numbers. The guide to what a Seismic Design Category actually means covers why a category is never a substitute for an engineer's assessment of one specific house.