I cleared back in at DFW twice recently.

Dec. One of the first people off the plane so no lines and no issues, we used Mobile Passport and were just waved to someone as there were no lines.

Jan 2. Arrived from Chile about the time ALL the South American flights arrive. Even though we were first off the aircraft the lines were massive from other flights At the end is a sign for Global Entry and Mobile passport. But you go down to the Mobile Passport line and it appears to dead end. However there is a swing door to put you into the front of the massive long line and no agent to indicate this or appease the crowd as you just walk in. Bottom line we were out of Immigration and Customs in minutes.

I have both Global Entry and Mobile Passport (FREE APP for EVERYONE). I find that Mobile Passport is faster as I don't have to stop get fingerprinted and answer questions with passport I answer the questions on the aircraft.

If you have Pre Check, when you come up the stairs from C&I it is several gates to the right. Clear is located at Terminal E. which is worthless.