On average, it is overwhelmingly clear that holding local election contests on the same day as federal elections in even years has many advantages, most notably higher turnout and lower administrative costs and burdens. However, every community, city, and state is different, and what may be right for one community may not work for another. This website exists, then, as a general resource.
As a scholar, I aim to provide useful, unbiased, rigorous quantitative analysis, as well as information from what other communities are doing around the nation, to help specific communities make wise decisions about when to hold elections -- those decisions are up to them. Over the years, I have created many city and state-specific local election timing analyses -- if you believe such an analysis might be useful for your state, or if you would like to learn the answer to any question you can't find on this site, please contact me at zhajnal@ucsd.edu.
Zoltan Hajnal, Professor of Political Science, UCSD