Hour 1.5 to 6: secure the house and decide

The house

• Safe room: interior and windowless (bathroom or closet). It holds a mattress, water, radio, flashlight, first aid kit and the pets' bag. Against a blast, an interior ground-floor room is right; against fallout, in a multi-story building an interior hallway on a middle floor is better, away from the roof and the ground (chapter 18).
• Curtains closed and, if there's a blast risk, stay away from windows. Taping them doesn't help.
• Extinguisher at hand, smoke and carbon monoxide detectors with batteries, and a flashlight in every room.
• Gas: shut it off only if authorities say so or you smell a leak.
• Cars parked facing out, keys in a fixed spot, backpacks and crates by the door.

The decision

Apply the trigger table (below). The rule: if the family leaves, it goes in the first 6 hours or waits for the first wave to pass. Between hour 6 and 24 is when the highways collapse.

Communication

• Check in every 3 hours by SMS with the out-of-area contact.
• Only one phone monitoring; the rest on power saving.
• NOAA radio on your area's frequency (find it at weather.gov/nwr); it also broadcasts civil alerts.
• Offline maps of your state and the states you'd drive through, already downloaded (chapter 19).

Pets

Collar with tag and phone number, leashes by the door, 30 days of food, vaccination record with current rabies and a microchip with up-to-date details. Without that, they can't get into many shelters or cross borders.

Personal safety

Low profile: nobody outside knows what's in your home. Move in pairs and never at night if there's a curfew. If a firearm is part of your plan, it must be legal, with training and locked up; if you don't have one, minute 0 is not the time to start (chapter 25).

Legal and paperwork

• Photos of every document onto the encrypted USB drive.
• If anyone in your household is a citizen of another country: register with their consulate for alerts and help, and keep its phone number handy.
• Selective Service: almost all men ages 18 to 25 living in the U.S., citizens or immigrants, must be registered. Check who it applies to in your household (sss.gov).