-------- Original Message --------
Subject:        USGS quad numbers
Date:   Mon, 23 Feb 2009 11:07:14 -0600
From:   Jenny Marie Johnson <[log in to unmask]>
Reply-To:       [log in to unmask]
To:     MAPS-L <[log in to unmask]>



I've been asked about a historic map numbering scheme for USGS quads.

The system would have been in use perhaps in the early 1970s.

15-minute quads were assigned a 1-3 digit number.  I believe that
Illinois index that I saw this on started the numbering in the NW corner
of the state and went across rows of quads from W to E and then back to
the W to begin the next line (in other words, numbers didn't seem to
zig-zag).

Within the 15-minute quads, the 7.5-minute quads were assigned letter
designations (A, B, C, or D) going in counterclockwise order starting
with the NE quad.

I don't know if this was an official scheme or if it was homegrown.  The
person who asked me thought that these alpha-numeric combinations were
used on USGS order forms.  Obviously, if it was an official scheme it
didn't last because USGS presented us with the 5-digit + letter + number
 scheme in the early/mid-1980s!

The scheme vaguely feels like some of the really old AMS numbering schemes.

Has anyone seen something like this for USGS quads?

Many thanks!

Jenny Marie Johnson
Map and Geography Library
University of Illinois at Urbana-Champaign
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217-333-3855