The following is not intended to be an essentials list. Rather, this is based on my experiences of living in Dallas.

Whistle
First aid kit - even something as simple as an AMK Ultralight .3 and a pair of scissors is helpful.
Medications - Rx and OTC beyond what you have in your FAK.
Water - have at least a bottle on your person. If you drive, keep a case of bottled water in your trunk.
Keep some food items on your person.
Kleenex pocket pack
Hand wipes or hand sanitizer - even in the city there are places where there is no running water such as at the porta potty or at the house of a friend who forgot to pay the water bill again.
Lip balm and sunscreen
Flashlight
Your tool of choice - if you're driving, have every tool in your car that it needs.
Wallet and cell phone
Bus schedules

Jeanette Isabelle
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I'm not sure whose twisted idea it was to put hundreds of adolescents in underfunded schools run by people whose dreams were crushed years ago, but I admire the sadism. -- Wednesday Adams, Wednesday