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Following the lead of other states, ‘squares' of approximately 3 miles on a side are based
on readily available 7.5 minute Quad topographic maps, dividing each map into 6
regions: top left, top right, center left, center right, bottom left and bottom
right. These divisions would result in squares approximately 3 miles on a side.
Note that the width of the square changes from the northern to the southern part
of the state because it is based on the longitude, which makes a triangle from
the north pole to the equator. In Utah County, the squares are approximately
3 1/4 miles wide and 2 7/8 miles high.
Utah is covered by 1541 7.5 minute maps, the edges of which overlap adjoining
states. This means there are over 9000 3x3 squares in the state. Since this is
an unmanagable number, only 1 square will be sampled for every 2 7.5 Minute Quad
topographic map, or 8.3% of the land area, yielding 770 squares.
For convenience, all possible squares are numbered based on numbering
the 7.5 minute Quad maps beginning at the top left corner of the state, proceeding
right, then down producing a 4 digit number; to which the square number,
1 to 6 is appended. The numbers 0, 7, 8, and 9 are not used. This yields a 5 digit number
identifying each square in the state. All birding organizations in the state will
use the same numbering scheme enabling data from each survey to be combined easily.
Square number 4 has been selected from every second Quad Topographic map. Since
the square chosen is arbitrary, alternate squares from the same topographic map
can be chosen if there is good reason.
A note about the maps. The northern and southern borders of Utah were supposed
to be on 42° or 37° respectively. They aren't, mostly because of the abilities of
the early surveyors. Apparently the law favors the original survey of a boundary,
so the borders have not been straightened. Due to this, many of the Quad maps along
the north and south borders of the state contain a small sliver of Utah land, and
therefore are not included in the selected squares, but are listed in the 7.5 minute
map listing for completeness.
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