Voter turnout in state elections is not significantly related to which of the following factors?

Voter turnout in state elections tends to be influenced by several key factors, one of which is the competitive nature of the race. However, the presence of a close division of officeholder parties does not significantly affect voter turnout in the same way other factors do. This is because the overall context of the election and the importance voters place on their engagement can vary widely. In some cases, even in a tightly contested race, voter turnout may not increase as expected if other motivating factors are weak, such as effective campaigning or broader interest in the issues.

The other factors listed, such as demographic characteristics of residents, voter registration rates, and high school completion rates, have been shown through research to significantly correlate with voter turnout. For instance, demographic characteristics can influence motivations and barriers to voting, while higher voter registration rates generally lead to increased participation. Similarly, higher education levels, indicated by high school completion rates, often correlate with greater civic engagement and voter turnout.

Therefore, a close division of officeholder parties is less impactful on voter turnout compared to these other well-established factors, making it the correct choice in this context.