Irish passport-holders travelling to the US face changes to the Visa Waiver Programme from 1 April.
The new requirements mean that those who travel from Ireland on the Visa Waiver Programme (VWP) must have an up-to-date electronic passport.
It also applies to those with passports who have a valid Electronic System for Travel Authorisation (ESTA).
The Irish Independent reports the Department of Foreign Affairs and Trade are estimating that about 170,000 Irish passport holders have traditional documents.
Those official travel papers were issued in 2006 from 30 March to 16 October and have not been replaced.
The first e-passports came on stream at that time and while the older varieties are still machine-readable, unlike the new passports, they don’t have a biometric chip.
Passengers can still travel to the US without valid electronic passports, but not on the VWP.
Such travellers will require non-immigration visas which are issued either in US embassies or consulates.
They must also attend there for interviews and then get the visa in their passports before their journey across the Atlantic.
See dublin.usembassy.gov for full details.