Storm & Ground pages are built from three kinds of sources:

  • public datasets for tornado records, soil and housing age
  • official city and state pages for local rules
  • published price lists and cost guides for prices

Every page lists its sources and the date each one was checked.

Tornado records: NOAA Storm Prediction Center

We use the Storm Prediction Center’s tornado database for 1950–2025. It is the file that includes county segments (the part of each tornado path inside each county). A tornado counts once for every county its path touched. So one storm can appear in several county totals. Ratings are for the whole track. The death figures are the direct deaths in the SPC record for the full path. Weak tornadoes were recorded less often in early decades. That makes counts of F3/EF3 and stronger the fairer comparison across years.

Soil: USDA Soil Data Access

Shrink-swell figures come from the USDA NRCS soil survey for each county. They were collected in October 2026. Each map unit (an area on the soil map) is classed by its main soil, using the USDA’s own scale. On that scale, a linear extensibility (how much the soil swells) of 6% or more is high, and 9% or more is very high. The results are county-wide shares, including rural land, and do not describe any single lot.

Housing age: U.S. Census Bureau

Housing-age figures come from the American Community Survey 5-year estimates for 2020–2024 (tables B25034 and B25035). They cover city limits only. They are survey estimates with margins of error, which are wider for smaller cities. They count all housing units, not only houses.

Rules: city and state pages

Permit fees, registration steps, the SoonerSafe rebate and licensing come from city websites, city fee schedules and ordinances, and Oklahoma state agency pages. Each one carries the date it was checked. Pages state only what these sources say.

Prices

Price ranges come from:

  • Oklahoma installers that publish their prices
  • manufacturer list prices
  • national cost guides (Angi, HomeGuide, Fixr)
  • the Ram Jack cost page
  • official fee schedules

Compare the stated inclusions and exclusions. Ask the company about anything the published price leaves unclear. We do not use other lead-generation sites as sources. A published range is not a quote.

How pages are checked and dated

Before a page is published, an editorial check compares its claims with the source notes. Claims without a source are taken out. The “Updated” date on a page is when it was last revised. Each source shows its own check date. Cities update fees and programs change, so ask the installer or repair company to confirm current permit fees in its written quote.