The county is a thin one
The Mine Safety and Health Administration lists the Ozark Quarry, with 25 employees, in Christian County, where 6 of 38 county-maintained structures are rated below legal loads — 15.8 per cent against a statewide county rate of 12.7 — and 7 carry a posting. The Strafford Quarry records 12.
This is Ozark Plateau country, where flat-lying Mississippian limestone is cut by deep narrow valleys and, since the 1910s, flooded by the White River reservoirs. The plateau surface has little relief and few streams to bridge, so the road networks here are among the thinnest in the state. But the reservoirs cut the routes that remain: an arm of a lake is a barrier with a crossing every several miles, so a market that looks circular on a map is really divided into lobes.
Around the Ozark Quarry, and across Phelps County, the same machines come up for sale for the same reasons.