Originally Posted by hfly
An emergency passport can be issued in a matter of hours and while they say it is to finish your current travel, is generally valid for a year, Furthermore, unless something has radically changed, it can be extended to full validity when you get home.
As you posted above:
Originally Posted by hfly
"U.S. Embassies and Consulates will continue to issue passports in emergency cases. Such passports will be limited in validity, and cannot be extended. Bearers will be required, however, to exchange their limited validity passports for a full-validity photo-digitized passport upon completion of their emergency travel, either through passport facilities in the U.S. Embassies and Consulates, or passport offices."
The timing of the exchange to a full-validity, photo-digitized passport is a little more open since the US government doesn't force you physically to show up and/or surrender it upon arrival to the US or to a destination where you can wait for the arrival of a full-validity, photo-digitized passport.
The validity of these limited-validity passports issued for "emergencies" is explicitly noted and is not for the full-term (usually 10 years, with notable exceptions); it's generally far less than even 5 years.
These changes came into effect after 9/11.