border preclearance
...that the U.S. maintains border preclearance facilities at a number of foreign ports and airports, whereby travellers pass through immigration and customs before boarding their plane or boat?
...that the <a href="./United_States" id="mwBHQ" rel="mw:WikiLink" title="United States">U.S.</a> maintains <b id="mwBHU"><a class="mw-redirect" href="./U.S._border_preclearance" id="mwBHY" rel="mw:WikiLink" title="U.S. border preclearance">border preclearance</a></b> facilities at a number of foreign ports and airports, whereby travellers pass through immigration and customs before boarding their plane or boat?