Lynden Township is the traditional name given to the Washington land survey township T 40 N, R 3 E including the portions of T 41 N, R 3 E up to the Canadian border, located in Whatcom County.
The City of Lynden is not considered part of Lynden Township.
The modern roads which delimit T 40 N, R 3 E (including portions of T 41 N, R 3 E) are as follows:
- On the north, the Canadian border.
- On the east, Trapline Road and its extension north-south.
- On the south, one mile north of the east-west portions of Pole Road.
- On the west, Guide Meridian Road.