Mean PopulationIf the United States was a tray of weights with each person
represented by an equal weight the mean center would be the point at which the map is completely balanced.
Median PopulationThe point at which there is an equal number of people to
the north and south and to the east and west.
Median Center of Population in the U.S.
1880 39.95 84.12
1890 40.0475 84.6669
1900 40.0589 84.8169
1910 40.1258 85.0333
1920 40.1978 84.7333
1930 40.1978 84.6097
1940 40.0717 84.6697
1950 40.0033 84.9475
1960 39.9403 85.2833
1970 39.7953 85.5286
1980 39.3167 86.1375
1990 38.9653 86.5314
Year Latitude Longitude
Median Center of Population
0
20
40
60
80
100
1850 1900 1950 2000
Year
Lat
itu
de
and
Lo
ng
itu
de
Series1
Series2
Median Center of Population Linear Regressions
• Latitude• y = -.0073046154x +
40.29095385
• Longitude• y = .016327028x +
84.19185513
Predicted Latitude for 2000: 39.4144
Predicted Longitude for 2000: 86.151098
Comparison of Our Predicted With the Actual Median Center
of Population
• We predicted that the latitude in 2000 would be 39.4144. It actually is 38.7.
• We predicted that the longitude in 2000 would be 86.151098. It actually is 87.2.
18 year old French Canadian Wife of a Potato Farmer in 1940