The Tax Foundation does an excellent job of tracking State and Local Tax Ballot Measures. They are the nations leading tax policy organization providing research and insightful analysis. The Tax Foundation tracks the results of each state ballot measure and offers analysis on the most notable ballot measures including Arizona Proposition 208, Colorado Proposition 116, Illinois Graduated Income Tax Amendment, property tax changes in California and Colorado, excise tax changes in Arizona, Colorado and Montana, and New Jersey and South Dakota Amendments to mention a few.