Township Line, PLSS Definition

Township lines are the east-west boundary lines that divide the PLSS survey area into horizontal rows (tiers) of townships. Each township line forms the north boundary of one tier of townships and the south boundary of the tier immediately above it. Township lines run true east-west and are parallel to the baseline, spaced six miles apart (with corrections applied at standard parallels).

The baseline itself is the most prominent township line — it separates townships numbered north from those numbered south. Standard parallels serve as township lines at 24-mile intervals, with the correction in grid alignment occurring at each one. Between the baseline and each standard parallel, four intermediate township lines divide the six-mile tiers.

Township lines, like section lines, have left a strong imprint on the rural American landscape. In areas where county roads follow the survey grid, township lines often correspond to roads that run due east-west with only minor interruptions. In Kansas, Nebraska, and the Dakotas in particular, the rhythm of roads spaced six miles apart — township-line roads — punctuates the grid of one-mile-apart section roads.

When reading a PLSS legal description, the township number tells you which township line forms the southern boundary of your township. "T3N" means the township is between the third and fourth township lines north of the baseline. Surveyors marking boundaries in the field will often reference township lines as control lines — the east-west line from which the six sections in a north-south row of sections are measured. Understanding which township lines are which is essential for navigating original BLM survey notes and plats.