There are 3 parts to a map sheet label; the map series, map areas, and map sheet.
– 1:1,000,000 scale map series, denoted by a number indicating its general position in the country (e.g., 85). The following map shows all the map series numbers for Canada.

– Each map series is divided into 1:250,000 scale map areas, denoted by a letter (e.g., J). You can find the map series and map areas for the Northwest Territories here.
– Each map area divided into 1:50,000 scale map sheets, denoted by a number (e.g., 01).

These numbers and letters are then combined to form a unique designator for a map sheet, in this case 85J01.

1:50,000 Topographic Map Sheets (see bottom of page for map)

Below are some common map sheets in the Yellowknife area:

For quick reference, below is a map of the Yellowknife area showing the map sheet labels (click to enlarge).