Latitude and Longitude are often defined in degrees, minutes, and seconds. There are
60 seconds in a minute and 60 minutes in a degree. The symbols are as follows

° = degrees
' = minutes
" = seconds

The following procedure may help you determine the Latitude and Longitude for your
site using a USGS Topographic Quadrangle [example].

STEP 1: Obtain a topographic map

There are a variety of ways to obtain a topographic map for your area:

• Many of your local camping and/or hunting stores will sell local topographic
  maps.
• State geologic surveys often sell topographic maps.
• Get the topographic map for your site online, from the USGS at Finding and Ordering USGS Topographic Maps
• Get the topograhic map from your local library.

STEP 2: Calculating Longitude

1.Look at the right side (upper or lower corner) under the map name, or the
second of two numbers separated by "x", to find the width scale (longitude) of
the map:
If "7.5 Minute Series" enter 450
If "15 Minute Series" enter 900
If "15x30 Minute Series" enter 900

_________________

2.Using a ruler, measure the width of your map east to west (Exclude the
borders)

__________________cm

3.Divide the #1 by #2 to the nearest whole number

________________cm/sec

4.Enter the Longitude located in the lower right hand corner

______________° ' "

5.Using a ruler, measure (cm) from your site, straight across to the right hand
side of the map.

_________________ cm

6.Multiply #5 by #3 (to the nearest whole number)

__________________

7.Convert #6 to minutes and seconds by dividing by 60. Your whole number after
division is the number of minutes, and the remainder is the number of seconds.
(Do not use a calculator) For example, 215 can be divided by 60 three times.
215-180=35. So 215 converts to 3'35".

___________________

8.Add #4 to #7

___________________

The answer to #8 is the Longitude of your site.

STEP 3: Calculating Latitude

1.Look at the right side (upper or lower corner) under the map name, or the
second of two numbers separated by "x", to find the width scale (longitude) of
the map:
If "7.5 Minute Series" enter 450
If "15 Minute Series" enter 900
If "15x30 Minute Series" enter 900

_________________

2.Using a ruler, measure the length of your map north to south (Exclude the
borders)

__________________cm

3.Divide the #9 by #10 to the nearest whole number

________________cm/sec

4.Enter the Latitude located in the lower right hand corner

______________° ' "

5.Using a ruler, measure (cm) from your site, straight down to the bottom of the
map.

_________________ cm

6.Multiply #11 by #13 (to the nearest whole number)

__________________

7.Convert #14 to minutes and seconds by dividing by 60. Your whole number
after division is the number of minutes, and the remainder is the number of
seconds. (Do not use a calculator) For example, 215 can be divided by 60 three
times. 215-180=35. So 215 converts to 3'35".

___________________

8.Add #15 to #12

___________________

The answer for #16 is the Latitude of your site.