The mobile ID can also be used as an alternative to a boarding pass. Further, it's being pioneered in conjunction with biometric facial recognition. A total of 14 airports and four airlines are currently participating in this TSA project. Specifically, these include Alaska Airlines, American Airlines, Delta Air Lines, and United Airlines. The latest airport to join the PreCheck Touchless ID programme is Denver International Airport. The state joins 15 others in recognising digital IDs, with travellers no longer required to provide physical means of identification. Other states participating in the mobile app project include Arizona, California, Colorado, Georgia, Hawaii, Iowa, Louisiana, Maryland, and New Mexico. Among others piloting the initiative are New York, Ohio, Puerto Rico, Utah, Virginia, and West Virginia.