These maps illustrate two major changes (greater urbanization of votes within the state, and increased participation in voting) in three Virginia presidential elections spanning 80 years: 1932, 1972 and 2012.
The first map above represents the 1932 election, in which only 12.30% of the 1930 population cast ballots–the shading shows the 36 localities in which this figure was less than 10%. The cartogram also shows that a large portion of the votes were cast in rural areas, with only a few distinct population centers.
By the 1972 election the cartogram shows the centralization of votes in metropolitan areas. Additionally, voting was not as sparse as in 1932. In this election 31.34% of the 1970 population cast ballots, and while there was still one county in which this figure remained under 20%, there were also six above 40%.
In the 2012 election the votes are even more predominantly located in the state’s metropolitan areas, and a comparison of this cartogram with 1972 makes especially clear the growth of Northern Virginia’s outer suburbs. Also, participation in the electorate had grown: 48.22% of the 2010 population cast ballots, with 38 localities over 50% and six over 60%.
Bonus maps: As a supplement, the following are unaltered maps showing the election results at the city/county level for the Presidential elections of 1932, 1972 and 2012 in Virginia.
Source of 1930 and 1970 population data: U.S. Census Bureau Population of Counties by Decennial Census: 1900 to 1990
Source of 2010 population data: U.S. Census Bureau 7/1/2015 County Population Estimates
Source of 1932, 1972 and 2012 election data: Virginia Department of Elections