Boost your paycheck income
North Checkpoint and South Checkpoint are two checkpoints around the combat zone that can be claimed to further the faction's paycheck. The checkpoints are captured by a player of either faction interacting with the flagpole at each checkpoint. Once the capture progress is completed, the checkpoint is claimed and a server-wide notification is broadcasted to all units advising them of who is now in control of that checkpoint.
Checkpoints add an additional $50 paycheck to the controlling faction.
The Abandoned Checkpoint is slightly different. It can only be captured by the Rebels as a way to restrict the Police Department's presence on the Drug Island. If this checkpoint is controlled by Rebels, APD units are not permitted to enter that island.
The Mayor can apply a "Reclaim lost territory" policy, in which the Abandoned checkpoint (or Rebel checkpoint) can be reclaimed. It is then converted into a Police Checkpoint, and will remain as such until the Mayor is killed or the server resets.
Once the Mayor is killed, it becomes an Abandoned Checkpoint once again, in which the Rebels can reclaim it... This checkpoint does not contribute towards any paycheck.