If you are creating a tactic for a political campaign, you can easily target congressional districts in the Location tab.
Note: You can add congressional district targets when you bulk edit tactic locations.
Click Location and open the Geopolitical tab.
Click the Add (+) button to add a congressional district or a state to your location targeting rules. You can search by state, district, or district code (e.g. "IL_02" will find Illinois' 2nd Congressional District).
Finalize your location targeting rules in the panel to the right, finish setting up your tactic, and click Save.