Does US Immigration Know When You Leave?
Yes! If you travel to a US state like Texas, among many others, US immigration can tell when you entered or left.
If you leave the US by air, the US processes passport details via a special system called APIS. This system was created to enhance border security. The APIS system provides US officials with departure and pre-arrival manifest data on everyone (passengers and crew) entering and leaving the US. APIS data is transmitted for all commercial air passengers departing and arriving in America.
It is even possible for someone who travels in/out of the US to check their travel history (entry and departure) online via the I-94 website. International travelers visiting the US can apply and retrieve their I-94 admission numbers/records as proof for legal visitor status. The website has maintained travel records for the past 5 years.
The records provided by the I-94 website reflect air travel and may not reflect arrivals or departures by land, closed-loop cruiser travel, air carrier reservation information/updates and USCIS updates, extensions/adjustments of status. What's more, lawful permanent resident travel isn't provided on the I-94 website.
However, an I-94 form is required by everyone except US citizens, returning resident aliens, aliens holding an immigrant visa, and majority of Canadian citizens visiting/in transit via land borders. Air & sea travelers are also required to fill I-94s as part of their admission process in a port of entry.
Generally, travel information via air, land, and sea is recorded. Since Customs and Border Protection documents move from many sources electronically, US immigration will know when someone leaves of enters the US regardless of the mode of transport they are using.
However, in the case where you exit the US through land, there is a possibility that Customs and Boarder Protection won't know when you leave. The reason behind this is - marine and airline passenger manifest records are readily accessible by CBP, but the same can't be said about records of passengers who exit through land.
The Form I-94 is an arrival and departure record issued by United States Customs & Border Protection to foreign visitors who are entering the US. The form is issued in paper or electronic form to track non-US citizens arriving or departing the US.
Form I-94 is a crucial document since it acts as proof that a foreigner is entering the US lawfully. It also indicates the date which a foreign visitor must leave the US. For years (up until 2013), most foreign visitors to the US received Form I-94 in paper form. Today, most foreign visitors get electronic travel records. If you travel via sea/air, you will receive the electronic form. However, individuals who travel by land will most likely receive I-94 in paper form.
It's worth noting that individuals who arrive at land border points have the option of applying for a I-94 provisional form a week or so before their arrival date. If you wish to get your travel history information with arrivals and departures, you can get your 1-94 form for free for records after April 2013.