Texas wasn't surveyed under the US Public Land Survey System, but various parts of it were divided into very similar one-mile squares, and counties were laid out in a similar regular fashion. Many Great Plains states have similar county boundaries.

The eastern third of the state was mostly divided (a century earlier) into Spanish land grants, whose boundaries were often perpendicular to the rivers. As a result, counties in east central Texas have angled boundaries—roughly 45 degrees off north.

The two systems come together in a patchwork just south of Arlington and Dallas that's visible on any street map. Arterial roads oriented north-south suddenly turn to follow the angled land grants.