The Princeton Election Consortium (PEC) is a private organization that has, for over a decade, been developing a comprehensive database to provide a unique view on the state of the American political environment, past, present, and future. 

With the PEC, you can track all national and state-level elections for nearly two decades, at the highest level of granularity. You can track results by date, district, county, party, and vote margin. Additionally, you can track electoral trends, by state and by election, over time.