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North Arrows pointing at true north or

September 23 2008 | 1 comment
Categories: Map Elements

I work at a headquarters office for a provincial government in Canada (Gov't of Alberta). As a result, we end up making mostly small scale maps that represent either the entire province, or large sections of it. 99% of the time we use a transverse mercator projection called 10TM that is meant to represent our province, which is 10 degrees of longitude wide, in the best way available. As a result, the east and west boundaries of our province appear to converge as you look nothward (see left side map of attached PDF). My question is; should north arrows point toward "page north" as ArcMap enables, even when true North is evidently in a different direction where the element is placed, or should north arrows follow an azimuth pointing to true north relative to where the element is placed? I find that it looks especially funny when the map includes no area that has page north and true north coincident (like in the right hand map of the attachement).

Mapping Center Answer:

In this case I would absolutely advise not to show a north arrow at all. If you're being forced, by the non-cartographically-informed-powers-that-be, to put a north arrow on that map, then definitely rotate it to true north. (Since your maps are all small to medium scale, there's no need to worry about indicating magnetic declination either).

The reason being is that every line of your graticule representing a meridian is pointing north.  Why, with all those lines, would you additionally need a north arrow?  Logically speaking, one would definitely not put a north arrow on a map with a graticule, and definitely not rotated in a fashion that contradicts the graticule.

It's also worth noting that you did at least put the north arrow on top of the data frame and oriented it so that it pointed north at its location.  It would be completely wrong to have placed a north arrow on this map, but off the data frame.  Note that on many topographic maps (for much larger scales), the location of the north arrow and magnetic declination indicator on the page is only valid for an imaginary line running straight up from that north arrow (usually there is note on the map explaining this as well).

We addressed this topic fairly generally in our blog entry called, Does every map need a north arrow and scale bar?

Using a north arrow with a graticule posted by Aileen Buckley on Sep 25 2008 1:11PM
If you do decide or are mandated to put a north arrow on your small scale maps, then placing a north arrow that shows all four cardinal directions (liek the north arrow you have on your map) in a quadrilateral that is formed by two parallels as well as two meridians that are visibly not vertical is possible. This gives map readers the clue that the orientation of north-south aligns with the meridians and the orientation of east-west aligns with the parallels.

On your maps, you could place the north arrows towards the top of the page rather than at the bottom since the angular distortion is more obvious farther north.

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