Flight delay compensation in United States

Denied boarding: what to do at the gate

1. Do not volunteer before you know the number. Volunteering removes the federal rule entirely and leaves you with whatever you agreed to.
2. If you are bumped involuntarily, the airline must give you a written statement of your rights. Ask for it — it is required, and asking signals you know the rule.
3. You are owed money, not a voucher. A voucher is something you may accept if it is worth more; at the gate it usually is not.
4. Payment is due on the day of the flight where practical, and by cheque within 24 hours otherwise.

And the refund rule, separately

If the airline cancels or moves your flight by more than three hours domestically and you decline the alternative, the refund of the unused portion is automatic and in your original form of payment — whatever the reason, weather included.

Checked bag liability on a domestic flight runs to roughly $3,800 per passenger. That is a ceiling on a claim for real losses, not an automatic payout, and it is considerably more than most people accept.