Robert Cushing based on Dave Leip's Atlas of U.S. Presidential Elections, Office of Management and Budget, and U.S. Census

Yes, the growing political divide in the United States has a geographic base. We can see that quite clearly in election results stretching back for more than a century.

The charts below show the percent of the Republican vote since 1912 by geography. (We used only Republican and Democratic votes for this calculation.) All the charts show that for most of the past century, the vote by place has jumped around.

But since the mid-1970s larger cities and their suburbs have grown steadily more Democratic. Meanwhile smaller cities, exurbs, suburbs of medium-sized metros and rural areas have grown steadily more Republican.

Let’s look at the most urban and the most rural places first. The chart at the top shows the percent of the presidential vote that went Republican. The red line are counties that today are non-metropolitan and not adjacent to any metro area. These are the nation’s most rural counties. The comprise 951 counties and 15.9 million people.

The blue line is the vote from central counties in the metropolitan areas of 1 million or more. These constitute 59 counties and about 91 million people. These are the most urban counties in the nation. You can see that since 1976 – and especially since 1992 – the gap between these counties has widened.

All the most rural counties (red) are going down one track, and the largest counties (blue) are going down another, with the 59 really big places becoming Democratic landslides in recent elections.

In the next chart, we’ve grouped all the county types that have rural and small-city characteristics, no matter what size metropolitan area they are in. Counties in this rural and small-urban category are the following:

  • Nonmetropolitan counties.
  • Counties in small metro areas (under 250,000 population).
  • Suburbs of medium-sized metros (counties outside the urban core in metros with 250,000 to under 1 million residents).
  • And the exurbs of large metro areas (these are counties that are officially part of a metro of 1 million or more people but where a majority of the population lives in a rural or nonurbanized setting).

You can see that since 1976 the trend in these counties is toward the GOP. There is some difference in how these diverse counties vote, but there’s an overall trend for the entire group.

Robert Cushing based on Dave Leip’s Atlas of U.S. Presidential Elections, Office of Management and Budget, and U.S. Census

Now, look at the nation’s most urban counties. The chart below shows:

  • The 59 counties in the central cities of metros of a million or more people.
  • The suburban counties in these giant metros.
  • The central city counties in metros of 250,000 to 1 million people.

As in the other charts, you can see the effects of the Reagan landslides in 1980 and 1984, but the trend is clear. These counties have grown less Republican over the last 12 presidential election cycles. The trend is most evident in the core counties of the nation’s largest metros (the blue line). But the trend is obvious in the suburbs of these major metros (orange line) and in the core counties of medium-sized metros (yellow line).

Robert Cushing based on Dave Leip’s Atlas of U.S. Presidential Elections, Office of Management and Budget, and U.S. Census

Trends last until they stop. But this trend has been alive and well for nearly 50 years. It is a political divide, yes, but it is also a divide by ways of life. And it shows no sign of abating.

Robert Cushing is a retired professor of sociology at the University of Texas Austin. He is the coauthor, with Bill Bishop, of The Big Sort: Why the Clustering of Like-Minded America Is Tearing Us Apart.