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Thread: Population density displayed by acres or square miles?

  1. #1
    Sep 2009
    Chicago, IL

    Population density displayed by acres or square miles?

    Just out of curiousity, can someone make a solid case for displaying pop density by square acres rather than square miles? I think people understand the square mile geography a lot better than square acres, which is why I always use square miles. But as I see density displays by square acre, I sure want to come to an understanding of why planner chose this option.

  2. #2
    Cyburbian Plus dvdneal's avatar
    Jan 2009
    Remote command post at local bar
    I can only guess at two reasons. There is always scale, if you're only looking at a couple of mile blocks, density by acre can give you more detail. I could also see it as helpful in looking for specifc du/ac. Especially in suburbs where there are sublte changes not shown in a square mile density. In the end, I would refer back to scale, if mile density shows what you need, good, if not get more detailed. Just my thought.

  3. #3
    Cyburbian mike gurnee's avatar
    Feb 1998
    Greensburg, Kansas
    The Census Bureau keeps density per square stats. That is the primary reason.

  4. #4
    Isn't the usual way these things presented is that its units per square acre and population per square mile?

  5. #5
    BWharrie's avatar
    Jul 2002
    Cross Country Skiing, Australia

    Depends on the user

    The designation should aim at to whom your audience is. Use the most appropriate is indicate by the regulations and add a conversion in brackets but go low. I have the same challenge here in regional Australia with hectares and metres(legal requirement) and imperial acres and feet/inches (which most of my clients can relate to, even though we converted to metric in the 1960's-70's.

    Whilst our planning codes state the metric ie 40 hectares or 900 millimetres I place the conversion in brackets)
    ie Height is limited to 1.0 metre (3 feet 3 inches) or less above the existing ground level. or Floor area limited to 10 square metres (107 square feet).
    With a covering statement at the bottom of the document "NB2: Metric measurements are the legislative amounts, imperial measurements are a converted guide only."
    Furthermore note that I use the affirmative positive context in wording avoiding the words "not" and "no" thereby focusing on what we want.

  6. #6
    Cyburbian Tobinn's avatar
    Aug 2005
    Clearwater, FL

    Acre vs Sq. Mile

    Isn't an acre already a "squared" (about 208.5 ft. by 208.5 ft.) figure?

    Anyway, I agree with the statement along the lines of using density per acre provides more detail than by sq. mi. Plus, it provides an easier number to working with (by acre, that is).

    There are 640 acres per square mile so if you were going to layout density requirements as units per sq.mi. you'd have something along these lines:
    For 7.5 du/ac that would be 4,800 du/sq.mi.

    Then, since most properties are measured in acres and fraction thereof, you'd always have conversions to make to figure out your density.
    At times like this, you have to ask yourself, "WWJDD?"
    (What Would Jimmy Durante Do?)

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