their cars for expedited land border controls. Unlike NEXUS, SENTRI is administered solely by the American government and does not provide expedited controls when entering Mexico. When entering United States by land from Canada, it can be used as a NEXUS card, but not the other way around. Individuals holding a NEXUS card may additionally register their cars for expedited land border controls under SENTRI. When entering United States by air, holders of SENTRI cards may use Global Entry kiosks to clear border controls at participating airports TSA PreCheck: TSA PreCheck is a trusted traveller programme initiated in December 2013 and administered by the U.S. Transportation Security Administration that allows selected members of select frequent flyer programs, members of Global Entry, NEXUS, and SENTRI, members of the armed forces, and cadets and midshipmen of the United States service academies After completing a background check, being fingerprinted, and paying an $85 fee, travellers will get a Known Traveler Number. TSA does not issue an ID card like Global Entry, NEXUS, and SENTRI do. Travelers are notified if they have PreCheck by having an indicator printed on their boarding pass that may say "TSAPRECHK", "TSA PRE", or "TSA Pre✓®" depending on the airline and type of boarding pass. As of December 2019, a total of 73 airlines were participating in the program. Local border traffic is the flow of travellers within the area surrounding a controlled international or internal border. In many cases local border traffic is subject to special regulations to expedite border controls for individuals travelling within local border areas. Depending on the particular border in question, these measures may be restricted to local residents, implemented as a blanket regional visa waiver by one jurisdiction for nationals of the other, restricted to frequent cross-border travellers, or available to individuals lawfully present in one jurisdiction seeking to visit the other. : For example, the relaxed border controls maintained by Bhutan for those not proceeding past Phuentsholing and certain other border cities enable travellers to enter without going through any document check whatsoever. America: The Border Crossing Card issued by American authorities to Mexican nationals enables Mexicans to enter border areas without a passport. Both United States and Bhutan maintain interior checkposts to enforce compliance. : China maintains relaxed border controls for individuals lawfully in Hong Kong or Macau to visit the surrounding Pearl River Delta visa-free provided that certain conditions are