Williston's Seismic Design Category, explained

Williston carries Seismic Design Category A under USGS's ASCE 7-16 model. Lowest seismic design category. Building code requires no seismic-specific detailing here beyond ordinary construction practice. That puts Williston in the 13th percentile nationally for seismic hazard - higher than 13% of the 4,875 US cities USGS was checked against here.

Where Williston sits in North Dakota

The raw figures: peak ground acceleration 0.037g, short-period spectral response 0.076g, 1-second spectral response 0.024g. Among 14 North Dakota cities in this dataset, Williston ranks 1 for seismic hazard, the 100th percentile within the state. About 28,821 people live in Williston, North Dakota.

What a retrofit costs in Williston

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

What this means for insurance

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 Williston address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Williston'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.