Something is afoot in Iowa. Not only have nearly 120,000 voters already cast their ballot, registered Democrats are returning their mail ballots at a higher rate than Republicans in nearly every Iowa county. This, in part, explains the approximately 5:3 partisan registration advantage Democrats have over Republicans among mail ballots returned so far in the Hawkeye state.
To see this more clearly, I plot mail ballots requested against the percent mail ballots returned for each county, as reported by the state. To isolate the comparative return rates of Democrats and Republicans, I only plot Democrats as a percentage of Democrats and Republicans, excluding all other registrants.
The graph shows that in nearly all counties, a greater percentage of Democrats have returned their mail ballots than Republicans, relative to the percentage who requested ballots. This is apparent by how the points on the scatterplot tend to fall above the diagonal line.
There is still plenty of time left for Republicans to return their mail ballots, so this early voting gap favoring Democrats may diminish as Election Day nears. However, Iowa confirms a pattern in Ohio, whereby the earliest voters in these states are tending to be more Democratic. Buckle your seats boys and girls, this ride is just getting started.