It is very important that everyone has some money saved for those unexpected emergencies. It is a hard and fast rule that emergencies will occur. One thing to think about is the need to have a certain amount of your emergency fund in cash stashed at home or in your 72-hour kit. People who have lived through natural disasters have learned that when the power is out for weeks at a time, cash is a necessary requirement. Stores are often willing to sell their goods, but can't access your funds through a debit or credit card. You'll have to decide how much to keep in cash, but be sure and have smaller size bills since people may have difficulty making change.
We've learned to hide it in hard-to-get places so we aren't tempted to raid the stash to pay for a babysitter or to give our kids allowance. We want it to be there if there ever was a TRUE emergency.
Just something to think about -