This scatter plot shows voter turnout and margins by county for the 2004-2016 presidential elections.
This visualization includes a search feature to allow users to filter by state or county, an option to explore "what-if" scenarios by clicking and dragging counties, and an option to weight the county bubble sizes by a variety of metrics.
More info here: https://pstblog.com/2017/06/05/national-election-vis.