USA and Canada - Mobile Passport Control:
If you are an American or Canadian citizen you can download the Mobile Passport Control (MPC) app to create a profile.
This will enable you to submit/upload passport information on arrival into the USA. You will then receive a QR code, and this will significantly speed up your journey through US immigration at selected airports.
Please be sure to check that your destination airport is supported by MPC.
You can download the MPC app here: https://www.cbp.gov/travel/us-citizens/mobile-passport-control.