Piney Woods map

Drive east out of Dallas or Houston and the change is gradual: blackland prairie gives way to a belt of post oak, and then, somewhere around the Trinity River, loblolly and shortleaf pine take over and stay until Louisiana. The ecological line runs roughly between I-45 and US-59, which is why Walker and Houston counties are counted here and the counties just west of them are not. Rainfall does the work: 45 inches a year in the north-west of the region, better than 55 in the south-east corner, the wettest ground in Texas.

The southern edge is the Big Thicket, where the pine forest meets the coastal plain in Hardin, Tyler and Polk counties, about 30 miles inland from Beaumont. Below that the ground flattens into the Gulf Coast prairie. In the north the pines thin out past Titus and Cass counties toward Texarkana and the Red River.

The Big Thicket is not a block of land but a scatter of them. Congress protected it in 1974 as Big Thicket National Preserve, the first national preserve in the national park system, and instead of one boundary it drew about fifteen separate units — nine tracts of land and six strips following creeks and rivers — across Hardin, Polk, Tyler, Jasper, Liberty and Orange counties, roughly 113,000 acres in all.

The reason for the odd shape is that the Thicket is a meeting place of habitats. Within a few miles you can walk from cypress slough to longleaf pine savanna to a hillside bog with carnivorous pitcher plants, because eastern hardwood forest, southern swamp, coastal prairie and central plains all reach their limit here. Nineteenth-century settlers went around it rather than through it, and it stayed a refuge for people avoiding conscription and the law well into the twentieth century.

Nearly all commercial timber cut in Texas comes from these counties. The bonanza period ran from the 1880s to the 1930s, when railroads reached the virgin longleaf and shortleaf stands and mill companies built whole towns around a saw — Diboll, founded by Southern Pine Lumber Company in 1894, is the surviving example. When the old growth was gone the industry replanted in loblolly plantations and moved into pulp, paper and plywood, which is what the mills at Lufkin, Diboll, Evadale and Orange still run on.

Oil arrived second and hit harder. In October 1930 a wildcat well called Daisy Bradford No. 3 came in near Henderson in Rusk County and opened the East Texas field — a single reservoir stretching more than 40 miles under Rusk, Gregg, Smith, Upshur and Cherokee counties, the largest oil field found in the lower 48 states up to that point. Tens of thousands of wells went down within a few years; at Kilgore, derricks stood shoulder to shoulder on a single downtown block still called the World's Richest Acre. The flood of cheap crude collapsed prices, the governor sent in the National Guard in 1931, and the Railroad Commission's response — rationing production well by well — set the pattern for oil regulation worldwide.