As of 30 September, most foreign travellers entering the US will be subject to the requirements of what is called the US-Visit scheme.
BBC News Online looks at the new procedures and explains how your experience of arriving and leaving the US is likely to change.
Q: What are the procedures?
This is the kind of fingerprint machine in operation
Upon arrival in the US, visitors are photographed with a digital camera and inkless prints are taken of both their right and left index fingers with a scanner. These biometric details are then automatically checked against those of suspected terrorists and criminals. If you don't appear to be any of these people, your details will be stored separately and you will be free to commence your stay in the US.
Ultimately, everyone will also be asked to "check out" when they leave the country. This will enable the authorities to find out whether someone is still in the US - and indeed is staying perhaps longer than permitted. Pilot exit procedures are currently operating at a number of air and sea ports to establish which procedure works best.
Q: Who does it affect?
The scheme has been running since January for residents of all countries requiring a visa for any length of stay in the US. As of 30 September, it will be extended to include countries in the Visa Waiver Program (VWP) - that is those states whose residents are not required to obtain a visa for business or pleasure trips to the US of up to 90 days.
Travellers from these states still won't require a visa for short trips, but they will now be fingerprinted and photographed to check their identity.
In addition, as of 26 October 2004, the passport carried by VWP country residents must be machine-readable, where personal information about you is typed with encoded marks and numbers, rather than being hand-written.
Theoretically, you will not be allowed in the US with a non-machine readable passport after 26 October 2004, but officials say they will not turn away those with old-style documents (provided they are valid), at least in the short term.
Q: And the VWP countries are?
Andorra, Austria, Australia, Belgium, Brunei, Denmark, Finland, France, Germany, Iceland, Ireland, Italy, Japan, Liechtenstein, Luxembourg, Monaco, Netherlands, New Zealand, Norway, Portugal, San Marino, Singapore, Slovenia, Spain, Sweden, Switzerland, and the United Kingdom.
Q: Are there any foreigners who are still exempt?
Canadian citizens will not be part of the scheme, although anyone travelling from Canada who is not Canadian will be. At least initially, Mexicans travelling on so-called Border Crossing Cards for trips under 30 days and within the 25-mile border zone will also be exempt.
Q: Is a machine-readable passport the same as a smart passport?
No. A smart passport contains biometric details - unique attributes of the human body, like a fingerprint, a picture of the eye or facial structure. US legislation requires all VWP countries to issue passports containing specific biometric details after 26 October 2005.
You will still however be able to enter the US on a non-biometric passport after 26 October 2005, as long as the document was issued before this date. Theoretically, therefore, you could still use a non-biometric passport until it expires - possibly as late as 2015 - although the Americans may have changed the rules again by then.
Q: Why are they so keen on biometric passports?
It makes it virtually impossible for anyone else to make use of the identity of a stolen passport as the biometric details wouldn't match.
Q: Does the US-Visit scheme make everything really slow?
Since deploying US-Visit at 115 airports and 14 seaports in January, more than 8.5 million foreign nationals have been processed without long waits, according to US officials responsible. They insist it takes just 15 seconds per arrival.
Q: Does the scheme compromise my privacy?
Well, obviously to the extent that identifying information about you is being gathered and stored. This is one of a number of measures which have been taken on the grounds of national security since the 11 September 2001 terrorist attacks.
The European Union earlier this year authorised airlines to hand over information about passengers headed for the US - including addresses, credit cards and e-mail details. Potentially, information about you will be checked against lists of suspected terrorists and criminals before you even set foot in the US.