Security measures taken by NYPD of US Postal Mailboxes locked up as prevention of possible terrorist bomb along parade route in NYC.
The locks over mailboxes so nobody can throw bombs in them. It is a reminder of how careful authorities are when it comes to keeping the crowds safe.
Locked which highlights the reality that our freedoms are constantly threatened. Someone who wanted to harm those at the parade could easily have dropped something dangerous inside that mailbox, which was right in the middle of a huge crowd of people.