The REAL ID Act, effective 2025. https://www.uspassporthelpguide.com/passport-required-domestic-air-travel/ https://www.uspassporthelpguide.com/passport-require

The REAL ID Act, effective 2025. https://www.uspassporthelpguide.com/passport-required-domestic-air-travel/ https://www.uspassporthelpguide.com/passport-required-domest... But OTOH there's a chart on this page that shows a longer term trend of nearly linear growth in US passport holder percentage from the 1990's: https://lindynewsletter.beehiiv.com/p/japan-gets-there-first-abc5 https://lindynewsletter.beehiiv.com/p/japan-gets-there-first...