Although the Mobile Passport has been out since 2014, it has not completely caught on as quickly as some of the other line skipping options available. As of press time, it is available in 25 airports and 2 additional ports of entry in the US.
The app was released by the US Customs and Border Patrol. It differs from two of their other programs; Global Entry and TSA Precheck. As indicated by the name, TSA Precheck is for checking in through security prior to boarding your plane. This is highly recommended for anybody who flies more than even a couple of times per year.
Global Entry takes it a step further with a priority entry line when getting back into the States after an international trip. That is where Mobile Passport comes in. Similarly to Global Entry, Mobile Passport gives you the chance to jump into a separate queue from the other passengers. Due to the fact that it isn't as widely adopted as Global Entry, it will only be useful if available in your airport, but if it is, by all means, use it.
So, does it work? Based on my experience, yes! In the busiest airport in the world (Atlanta), I breezed through! Twice now I have come off of a full flight and completely bypassed the line. If I didn't have to wait an hour for my bags it would have been a major win, but that's another story. I recommended that you start filling out the form prior to taking off and submit once you land. It is basically the same form that you fill out to declare anything you purchased while abroad.
Once you deplane, follow the signs. If you don’t see a sign, ask. It's that simple.
For a complete list of airports that offer Mobile Passport, see below:
Ft. Lauderdale (FLL)
Houston (HOU and IAH)
Los Angeles (LAX)
New York (JFK)
Port Everglades (PEV)
San Diego (SAN)
San Francisco (SFO)
San Jose (SJC)
Washington, DC (IAD)