Sinkhole risk in Franklin County, IL: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

On soluble rock: 0%
At or near the surface: 0%
Buried under cover: 0%

The next step for one property

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

Across 409 square miles, under one square mile of Franklin County maps onto soluble rock. With about 37,033 residents (91 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 374 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Franklin County

The nearest county rated sinkhole country is Union County, IL, about 39 miles southwest, close enough that the same rock may run under the county line. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Williamson County, IL 18 mi south · 0% at surface
Jefferson County, IL 21 mi north · 0% at surface
Hamilton County, IL 22 mi east · 0% at surface
Perry County, IL 25 mi west · 0% at surface
Saline County, IL 27 mi southeast · under 1% at surface
Jackson County, IL 29 mi southwest · under 1% at surface

Against the rest of Illinois

Franklin County ranks 50 of 102 in Illinois for soluble rock at the surface, and sits above 0% of US counties on that measure.