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Historic Values of Compass Declination


31 Mar 2015

What is declination?

Magnetic compasses point to magnetic north, not geographic north (the north pole). Magnetic north is currently located in far northern Canada, and its exact location is constantly, slowly changing.

As you stand facing the direction your compass calls North, true north is usually somewhere to the right or left. The amount of difference is called the declination and it is measured in degrees. The amount of declination depends both on where on the planet you are located, and the year you make the measurement.

Since surveyors used compasses to determine the direction of survey lines the parcels they surveyed were referenced to magnetic north. But as shown above, magnetic north is not the same as true north. When you try to fit an old survey on a modern map you'll find that in many cases the plot must be rotated clockwise or counterclockwise before it will fit. The amount of rotation that must be applied is known as the declination error, and corresponds to the number of degrees of compass declination that were in force when the surveyor made the survey measurements.

What was the compass declination in colonial times?

How much must your plots be corrected by? That, again, depends on your locale and the time period. A common method for determining the needed correction is to use trial and error correction using parcels that are known to be located on rivers and creeks. Using DeedMapper and its compatible maps you can apply different declination values to parcels in order to determine the 'best fit' value of declination.

Another method is to look at historical values of declination.

NOAA has an interactive map that shows declination changes over time going back hundreds of years.

We've used an early version of their calculator to generate tables of historic declination values for the following U.S. cities in the "metes and bounds" states. We've grouped the cities according to their rough latitude. You can estimate values for other locales by using the values for the nearest city to the east and west of your locale.

Accuracy of the table data is generally within one-half degree (30 minutes), but the presence of natural or artificial disturbances could cause differences of several degrees. Where data are not available "na" is listed. The letter E denotes east declination, W west. For example, 6W means magnetic north lies 6 degrees west of true north.

Surveys in locales having West declinations must be rotated counterclockwise while surveys in locales having East declinations must be rotated clockwise to fit on modern maps accurately. Corrections to within one degree of actual are usually satisfactory. It is generally hard to notice the effect of one degree of rotation or less except on parcels extending over long distances.

Sources of data

Values from 1955 through 1967.5 were derived using the source data of Table 4 of the "Coast and Geodetic Survey Publication 40-2, United States Magnetic Tables for 1960.0". Values subsequent to 1967.5 were calculated from the proper U.S. geomagnetic model obtained from the U.S. Geological Survey Branch of Global Seismology and Geomagnetism. Declination values for 1970 are from the U.S. polynomial model which produced map I-911, Magnetic Declination in the United States Epoch 1975. Declination values for 1975 are from the U.S. polynomial model which produced map I-1283, Magnetic Declination in the United States Epoch 1980. Declination values from 1980 to the present are derived from the spherical harmonic models USCON80, USCON85, and USCON90.

Tables of Historic Declination Values


-------------------------------------------------------
	  LAT:   44 DEG      18 MIN  NORTH
	 LONG:   69 DEG      46 MIN  WEST 
	 CITY & STATE:  Augusta, ME	     
-------------------------------------------------------
	YEAR      DECLINATION
	1750        9   56  WEST  
	1760        9   37
	1770        9   26
	1780        9   28
	1790        9   36
	1800        9   58
	1810       10   26
	1820       11    3
	1830       11   45
	1840       12   30
	1850       13   18
	1860       14    3
	1870       14   34
	1880       15    3
	1890       15   21
	1900       15   46
	1910       16   39
	1920       17   25
	1930       18    5
	1940       18   21
	1950       18   17
	1960       18   12
	1970       17   57
	1980       17   52
	1990       17   30
	2000       17   28


 
-------------------------------------------------------
	 LAT:   42 DEG      21 MIN  NORTH
	LONG:   71 DEG       3 MIN  WEST 
	CITY & STATE:  Boston, MA	      
-------------------------------------------------------
	YEAR      DECLINATION
	1750        7   42  WEST  
	1760        7   16
	1770        6   59
	1780        6   51
	1790        6   52
	1800        7    5
	1810        7   25
	1820        7   53
	1830        8   29
	1840        9   11
	1850        9   56
	1860       10   38
	1870       11   12
	1880       11   45
	1890       12    9
	1900       12   40
	1910       13   36
	1920       14   23
	1930       15    7
	1940       15   24
	1950       15   22
	1960       15   24
	1970       15   24
	1980       15   39
	1990       15   42
	2000       15   54



-------------------------------------------------------
	LAT:   41 DEG      46 MIN  NORTH
	LONG:   72 DEG      40 MIN  WEST 
	CITY & STATE:  Hartford, CT	    
-------------------------------------------------------
	YEAR      DECLINATION
	1750        6   31  WEST  
	1760        5   58
	1770        5   34
	1780        5   18
	1790        5   13
	1800        5   17
	1810        5   31
	1820        5   53
	1830        6   25
	1840        7    4
	1850        7   46
	1860        8   27
	1870        9    4
	1880        9   41
	1890       10    8
	1900       10   42
	1910       11   35
	1920       12   21
	1930       13    5
	1940       13   21
	1950       13   19
	1960       13   24
	1970       13   32
	1980       14    1
	1990       14   20
	2000       14   43



-------------------------------------------------------
	LAT:   43 DEG       9 MIN  NORTH
	LONG:   77 DEG      36 MIN  WEST 
	CITY & STATE:  Rochester, NY	   
-------------------------------------------------------
	YEAR      DECLINATION
	1750        5    9  WEST  
	1760        4   25
	1770        3   43
	1780        3    9
	1790        2   44
	1800        2   30
	1810        2   27
	1820        2   36
	1830        2   56
	1840        3   26
	1850        4    0
	1860        4   38
	1870        5   18
	1880        6    7
	1890        6   45
	1900        7   23
	1910        8    5
	1920        8   47
	1930        9   28
	1940        9   37
	1950        9   27
	1960        9   30
	1970        9   46
	1980       10   33
	1990       11   11
	2000       11   52



-------------------------------------------------------
	LAT:   40 DEG      45 MIN  NORTH
	LONG:   73 DEG      59 MIN  WEST 
	CITY & STATE:  New York, NY	    
-------------------------------------------------------
	YEAR      DECLINATION
	1750        5   10  WEST  
	1760        4   32
	1770        4    2
	1780        3   41
	1790        3   30
	1800        3   30
	1810        3   38
	1820        3   56
	1830        4   24
	1840        5    0
	1850        5   40
	1860        6   20
	1870        6   58
	1880        7   37
	1890        8    7
	1900        8   42
	1910        9   32
	1920       10   16
	1930       11    0
	1940       11   14
	1950       11   13
	1960       11   22
	1970       11   40
	1980       12   20
	1990       12   56
	2000       13   29



-------------------------------------------------------
	LAT:   39 DEG      56 MIN  NORTH
	LONG:   75 DEG       9 MIN  WEST 
	CITY & STATE:  Philadelphia, PA	
-------------------------------------------------------
	YEAR      DECLINATION
	1750        4   13  WEST  
	1760        3   35
	1770        3    3
	1780        2   37
	1790        2   23
	1800        2   18
	1810        2   22
	1820        2   36
	1830        3    0
	1840        3   31
	1850        4    8
	1860        4   45
	1870        5   23
	1880        6    2
	1890        6   34
	1900        7    9
	1910        7   54
	1920        8   35
	1930        9   17
	1940        9   29
	1950        9   28
	1960        9   40
	1970       10    5
	1980       10   56
	1990       11   42
	2000       12   24



-------------------------------------------------------
	LAT:   39 DEG      17 MIN  NORTH
	LONG:   76 DEG      36 MIN  WEST 
	CITY & STATE:  Baltimore, MD	   
-------------------------------------------------------
	YEAR      DECLINATION
	1750        2   54  WEST  
	1760        2   15
	1770        1   40
	1780        1   12
	1790        0   54
	1800        0   45
	1810        0   46
	1820        0   57
	1830        1   17
	1840        1   46
	1850        2   21
	1860        2   58
	1870        3   38
	1880        4   18
	1890        4   52
	1900        5   29
	1910        6   12
	1920        6   49
	1930        7   29
	1940        7   39
	1950        7   37
	1960        7   51
	1970        8   23
	1980        9   23
	1990       10   19
	2000       11    9



-------------------------------------------------------
	LAT:   40 DEG      26 MIN  NORTH
	LONG:   80 DEG       0 MIN  WEST 
	CITY & STATE:  Pittsburgh, PA	  
-------------------------------------------------------
	YEAR      DECLINATION
	1750         NA
	1760         NA
	1770         NA
	1780         NA
	1790        0   42  EAST  
	1800        0   58
	1810        1    4
	1820        1    0
	1830        0   45
	1840        0   20
	1850        0   10  WEST  
	1860        0   45
	1870        1   24
	1880        2    6
	1890        2   46
	1900        3   23
	1910        3   57
	1920        4   28
	1930        5    4
	1940        5    8
	1950        5    0
	1960        5   12
	1970        5   46
	1980        6   55
	1990        7   58
	2000        8   56



-------------------------------------------------------
	LAT:   37 DEG      32 MIN  NORTH
	LONG:   77 DEG      26 MIN  WEST 
	CITY & STATE:  Richmond, VA	    
-------------------------------------------------------
	YEAR      DECLINATION
	1750        1   22  WEST  
	1760        0   44
	1770        0   11
	1780        0   16  EAST  
	1790        0   34
	1800        0   43
	1810        0   44
	1820        0   35
	1830        0   16
	1840        0   11  WEST  
	1850        0   45
	1860        1   21
	1870        2    1
	1880        2   40
	1890        3   15
	1900        3   51
	1910        4   31
	1920        5    2
	1930        5   38
	1940        5   47
	1950        5   47
	1960        6    6
	1970        6   47
	1980        7   57
	1990        9    0
	2000        9   58



-------------------------------------------------------
	LAT:   37 DEG      16 MIN  NORTH
	LONG:   79 DEG      56 MIN  WEST 
	CITY & STATE:  Roanoke, VA	     
-------------------------------------------------------
	YEAR      DECLINATION
	1750        0    6  WEST  
	1760        0   34  EAST  
	1770        1   10
	1780        1   40
	1790        2    3
	1800        2   18
	1810        2   22
	1820        2   17
	1830        2    3
	1840        1   40
	1850        1   11
	1860        0   37
	1870        0    1  WEST  
	1880        0   41
	1890        1   19
	1900        1   54
	1910        2   26
	1920        2   50
	1930        3   20
	1940        3   24
	1950        3   20
	1960        3   40
	1970        4   26
	1980        5   44
	1990        6   54
	2000        8    0



-------------------------------------------------------
	LAT:   38 DEG      21 MIN  NORTH
	LONG:   81 DEG      37 MIN  WEST 
	CITY & STATE:  Charleston, WV	  
-------------------------------------------------------
	YEAR      DECLINATION
	1750        0   11  EAST  
	1760        0   51
	1770        1   30
	1780        2    3
	1790        2   30
	1800        2   48
	1810        2   56
	1820        2   53
	1830        2   42
	1840        2   21
	1850        1   54
	1860        1   21
	1870        0   44
	1880        0    4
	1890        0   36  WEST  
	1900        1   11
	1910        1   39
	1920        2    2
	1930        2   30
	1940        2   31
	1950        2   25
	1960        2   41
	1970        3   25
	1980        4   45
	1990        5   52
	2000        6   58



-------------------------------------------------------
	LAT:   38 DEG       2 MIN  NORTH
	LONG:   84 DEG      29 MIN  WEST 
	CITY & STATE:  Lexington, KY	   
-------------------------------------------------------
	YEAR      DECLINATION
	1750         NA
	1760         NA
	1770         NA
	1780         NA
	1790         NA
	1800        4   29  EAST  
	1810        4   40
	1820        4   43
	1830        4   37
	1840        4   21
	1850        3   58
	1860        3   28
	1870        2   54
	1880        2   14
	1890        1   32
	1900        0   59
	1910        0   39
	1920        0   23
	1930        0
	1940        0    5
	1950        0   13
	1960        0    4  WEST  
	1970        0   51
	1980        2   16
	1990        3   21
	2000        4   30



-------------------------------------------------------
	LAT:   35 DEG      46 MIN  NORTH
	LONG:   77 DEG      38 MIN  WEST 
	CITY & STATE:  Raleigh, NC	     
-------------------------------------------------------
	YEAR      DECLINATION
	1750        0   22  WEST  
	1760        0   14  EAST  
	1770        0   46
	1780        1   11
	1790        1   29
	1800        1   37
	1810        1   37
	1820        1   29
	1830        1   10
	1840        0   44
	1850        0   12
	1860        0   24  WEST  
	1870        1    4
	1880        1   41
	1890        2   16
	1900        2   51
	1910        3   30
	1920        3   58
	1930        4   31
	1940        4   40
	1950        4   42
	1960        5    5
	1970        5   53
	1980        7    9
	1990        8   14
	2000        9   17



-------------------------------------------------------
	LAT:   35 DEG      35 MIN  NORTH
	LONG:   82 DEG      33 MIN  WEST 
	CITY & STATE:  Asheville, NC	   
-------------------------------------------------------
	YEAR      DECLINATION
	1750        1   42  EAST  
	1760        2   21
	1770        2   57
	1780        3   30
	1790        3   55
	1800        4   13
	1810        4   21
	1820        4   20
	1830        4   10
	1840        3   51
	1850        3   26
	1860        2   54
	1870        2   18
	1880        1   38
	1890        0   58
	1900        0   26
	1910        0    1
	1920        0   12  WEST
	1930        0   33
	1940        0   31
	1950        0   27
	1960        0   50
	1970        1   43
	1980        3    9
	1990        4   17
	2000        5   29



-------------------------------------------------------
	LAT:   35 DEG      57 MIN  NORTH
	LONG:   83 DEG      55 MIN  WEST 
	CITY & STATE:  Knoxville, TN	   
-------------------------------------------------------
	YEAR      DECLINATION
	1750        2   11  EAST  
	1760        2   50
	1770        3   28
	1780        4    2
	1790        4   29
	1800        4   48
	1810        4   58
	1820        4   59
	1830        4   52
	1840        4   35
	1850        4   11
	1860        3   41
	1870        3    6
	1880        2   26
	1890        1   45
	1900        1   13
	1910        0   53
	1920        0   42
	1930        0   23
	1940        0   28
	1950        0   33
	1960        0   11
	1970        0   42..WEST  
	1980        2   10
	1990        3   17
	2000        4   29



-------------------------------------------------------
	LAT:   36 DEG       9 MIN  NORTH
	LONG:   86 DEG      46 MIN  WEST 
	CITY & STATE:  Nashville, TN	   
-------------------------------------------------------
	YEAR      DECLINATION
	1750         NA
	1760         NA
	1770         NA
	1780         NA
	1790         NA
	1800        6   10  EAST  
	1810        6   24
	1820        6   31
	1830        6   29
	1840        6   18
	1850        5   59
	1860        5   32
	1870        5    2
	1880        4   22
	1890        3   40
	1900        3    9
	1910        2   57
	1920        2   51
	1930        2   36
	1940        2   45
	1950        2   54
	1960        2   34
	1970        1   43
	1980        0   14
	1990        1    2
	2000        2   13



-------------------------------------------------------
	LAT:   34 DEG       0 MIN  NORTH
	LONG:   81 DEG       2 MIN  WEST 
	CITY & STATE:  Columbia, SC	    
-------------------------------------------------------
	YEAR      DECLINATION
	1750        1   41  EAST  
	1760        2   17
	1770        2   52
	1780        3   21
	1790        3   43
	1800        3   57
	1810        4    2
	1820        3   58
	1830        3   46
	1840        3   25
	1850        2   58
	1860        2   26
	1870        1   49
	1880        1    9
	1890        0   32
	1900        0    1  WEST  
	1910        0   29
	1920        0   42
	1930        1    4
	1940        1    4
	1950        1    3
	1960        1   30
	1970        2   27
	1980        3   53
	1990        5    3
	2000        6   17



-------------------------------------------------------
	LAT:   33 DEG      45 MIN  NORTH
	LONG:   84 DEG      23 MIN  WEST 
	CITY & STATE:  Atlanta, GA	     
-------------------------------------------------------
	YEAR      DECLINATION
	1750        2   53  EAST  
	1760        3   30
	1770        4    6
	1780        4   40
	1790        5    6
	1800        5   26
	1810        5   36
	1820        5   38
	1830        5   32
	1840        5   17
	1850        4   55
	1860        4   25
	1870        3   52
	1880        3   12
	1890        2   32
	1900        2    2
	1910        1   45
	1920        1   41
	1930        1   28
	1940        1   34
	1950        1   38
	1960        1   13
	1970        0   15
	1980        1   14  WEST
	1990        2   23
	2000        3   38


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