To order aerial photographs, a complete legal land description is important. The legal land description pinpoints the area required. If the legal land description of a parcel of land is unknown, it can be determined from a variety of maps available through private map dealers in the province.

The Air Photo Distribution Office can provide maps for reference use by on-site clients only.

Alberta Township Survey (ATS)

Any parcel of land in Alberta can be located by its legal land description. Legal land descriptions are based on the Alberta Township Survey (ATS) system. The ATS is a grid network dividing the province into equal-sized parcels of land.

Under the ATS, land is designated as being west of the 4th, 5th, or 6th Meridians (110°, 114°, 118° west longitude, respectively).


Between meridians are six-mile-wide columns called ranges. Ranges are numbered consecutively from east to west starting at Range 1 west of each meridian.


Townships are six-mile-wide rows that intersect ranges and are numbered consecutively from Township 1 at the Montana border to Township 126 at the Northwest Territories border. The term township also describes the six-by-six mile square formed by the intersection of ranges and townships.

Sections, quarters and legal subdivisions

Townships are divided into 36 sections, each section measuring one-by-one mile. Sections can then be divided into quarters (NE, NW, SE, SW), or into 16 legal subdivisions (LSD), as indicated.

Alberta Township Survey map, showing sections

The legal description of the section highlighted in the diagram above would be written as:

1 - 87 - 18 - W4
Sec. Twp. Rge. Meridian


Comments regarding the Air Photo webpages may be directed to:

  • Syd Wood , Air Photo Distribution Technologist, Air Photo Services