W. T. Carter continued the sawmilling legacy of his father, Joseph John Carter, beginning in 1876. The Carter mill had previously operated at various times during the late 1860s and early 1870s, in several Trinity County locations. Ownership of the mill was passed to W. T. Carter in 1876. From its first site, the mill was moved two miles to the west on Shaw family land, and then a mile southeast of the Trinity railroad station, being situated 4.5 miles north of Riverside in an 1880 Chicago lumber publication.
According to Pat Jones, the reason for the moving of the mill was simple; it was easier to bring the mill to the timber rather than the timber to the mill. Logging was done with animals pulling wagons along a wooden tram road.
Carter had been buying timber land in Tyler County as the construction of the Trinity & Sabine moved to the east. The T&S joined the Sabine & East Texas railroad at Colmesneil. In 1882, Carter bought out Alf W. Morris's sawmill located on the Williams League in Polk County. There he developed the Barnum site, adjacent to the tracks of the Trinity & Sabine.
The Northwestern Lumberman listing of 1880 placed the W. T. Carter mill four and a half miles north of Riverside.