4 min read

Wisconsin's aging electorate

Wisconsin’s population is aging, but its registered voters are aging even faster. The table below compares the ages of registered voters in early October from 2010 to now. Each age group has two columns. The first shows what percent of all registered voters is made up by that age group. The second shows the difference between that group’s share of registered voters and their share of the population.1 Negative numbers indicate that the age group is underrepresented among registered voters. Positive numbers mean there are disproportionately more voters in that age range.

The overrepresentation of voters ages 65+ has more than doubled from 2010 to 2018. The underrepresentation of voters under 35 has likewise increased substantially.

Table 1: Early October registered voters by age, compared to that age groups share of the adult population
ages 18 - 24
ages 25-34
ages 35 - 49
ages 50 - 64
ages 65+
year % of reg. voters % registered - % of pop. % of reg. voters % registered - % of pop. % of reg. voters % registered - % of pop. % of reg. voters % registered - % of pop. % of reg. voters % registered - % of pop.
2010 8.4 -4.3 15.9 -0.6 26.2 -0.5 28.8 2.5 20.7 2.8
2011 8.4 -4.2 15.5 -1.2 25.3 -0.6 29.6 2.8 21.3 3.2
2012 8.8 -3.9 16.0 -0.7 24.6 -0.5 29.2 2.3 21.5 2.7
2013 9.2 -3.3 15.3 -1.3 23.9 -0.6 29.5 2.2 22.1 3.0
2014 7.9 -4.6 15.4 -1.1 23.6 -0.4 29.9 2.5 23.2 3.6
2015 7.8 -4.7 15.4 -0.7 23.3 -0.7 29.8 2.5 23.8 3.7
2016 8.6 -3.9 15.7 -0.5 23.0 -0.4 29.2 1.9 23.5 2.9
2017 8.8 -3.6 14.5 -1.6 22.8 -0.7 29.3 2.5 24.6 3.4
2018 7.2 -5.2 13.1 -3.0 22.6 -0.9 30.2 3.3 27.0 5.8
Note:
Percent of the population for 2018 is calculated using the 2017 1-year ACS. For other years, the appropriate annual 1-year ACS estimate is used.

In October 2014, prior to the last gubernatorial election, electors 50 and up constituted 53% of all registered voters in Wisconsin despite only representing 47% of the adult population. Twenty-nine percent of Wisconsin adults are under age 35 but they only made up 23% of registered voters.

This year, the gap has widened. Registered voters under 30 are underrepresented by 8%. Voters in their fifties and up are overrepresented by 9%.

The graph below shows the age contours of Wisconsin’s electorate for every date with available data–not just the early October dates in the table above. Values in this graph correspond with the “% of reg. voters” columns.

The age of Wisconsin's electorate

Figure 1: The age of Wisconsin’s electorate

Purges of the voter rolls and their effect on different age groups

This next graph shows the under/over representation of those same age groups. These values correspond to the “% of registered minus % of pop.” columns.

The over/under represenation of age groups in Wisconsin's electorate

Figure 2: The over/under represenation of age groups in Wisconsin’s electorate

Notice the dramatic changes in 2017 and again at the beginning of 2018. These have two different causes. The first change (in mid-2017) is the statutory 4-year purge process.2 All electors who don’t cast a ballot for four years are mailed a card after each general election. Anyone who doesn’t respond is purged. So the steep drop-off for 25-34 year-olds represents people who voted in 2012, but not since then. Notice that this steep decline doesn’t exist for those 18-24. That’s because few of them were even registered in 2012 and are thus ineligible for the 4-year purge. The steady decline over the course of 2017 represents people turning 25 faster than their younger peers are registering.

The second drop-off (in early 2018) is the Election Commission’s purge of voters who they believed had changed addresses (based on administrative record matching conducted by the non-profit ERIC). Unsurprisingly, this had the greatest effect on voters under 35. Older voters, by comparison, were less likely to get caught up in this purge, so their relative share of the electorate increased.

After problems were revealed with the ERIC process, the Election Commission instituted supplemental voter rolls containing the registrations of all electors de-registered in that early 2018 purge. More recently, the Elections Commission also allowed municipal clerks to reinstate the registrations of tens of thousands of electors who they believe were erroneously removed in the mid-2017 4-year purge process. These actions may mitigate somewhat the unusually large discrepancies between age groups visible above.


  1. I choose not to show registration rates because procedures for maintaining voter registrations lists have changed in the past 8 years, rendering comparisons across time innacurate.

  2. Elections officials understandably avoid the word “purge.” In the official literature it is called the “Four Year Voter Record Maintenance.”