On Facebook, Nobody Knows You’re a Voter. Well, Almost Nobody.

Your Facebook profile doesn’t have boxes to check which political party you belong to or whether you voted in the last election. But political organizations who already know that can now deliver Facebook ads to fit your political preferences.

At least two statewide campaigns during the past year have used the new tool, “Custom Managed Audiences,” to reach Facebook users who are registered voters or political supporters. Linking the two isolated sets of data and teasing out information on voter preferences and opinions is a new front in microtargeting. Even smaller campaigns could use the technique to sway small but crucial sets of voters with very specific messages. Facebook’s most notable achievement may be that it makes some of the sophisticated approaches used during the 2008 and 2012 presidential campaigns affordable to other kinds of political contests.