A Note on Calculating Voter Turnout

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Because of a recent change in Colorado law, this abstract marks a change in the method used to calculate voter turnout. Previously, turnout percentage had been calculated based on the total number of active registered voters rather than the total number of registered voters—which includes both active and inactive voters. In 2012, the General Assembly amended the law to require that turnout be calculated as a percentage of all registered voters. This abstract reflects the new law.

Calculating turnout as a percentage of all registered voters more accurately represents true turnout, because it accounts for inactive voters. Inactive voters are eligible to vote and every election includes inactive voters who do cast their ballots. But because all registered voters are now included in the calculation, a comparison of voter turnout from the 2012 General and Primary Elections with turnout from previous years’ elections could lead to the incorrect conclusion that voter turnout decreased significantly in 2012. To avoid confusion, we have included additional tables in the turnout section at the end of this abstract showing the turnout calculation using both methods—the old and the new. The following is an example of the differences you will see when comparing the two calculation methods:


2012 General Election Turnout
(calculated as a percentage of active voters)

County Active Voters Ballots Cast Turnout %
Adams 189,069 177,945 94.12%
Alamosa 7,152 6,837 95.60%
Arapahoe 310,775 288,033 92.68%
Archuleta 7,195 6,805 94.58%


2012 General Election Turnout
(calculated as a percentage of registered voters)

County Registered Voters Ballots Cast Turnout %
Adams 258,272 177,945 68.90%
Alamosa 10,013 6,837 68.28%
Arapahoe 384,522 288,033 74.91%
Archuleta 10,179 6,805 66.85%