Originally Posted by
B747-437B
Mexico is considered "contiguous territory" with the United States and therefore, in addition to having a ticket that exits the USA you MUST also have either a residence permit for Mexico or else a ticket that exits Mexico to a point outside "contiguous territory" within 90 days of your entrance to the USA in order to be eligible to use the VWP. Alternatively, you should apply for a B1/B2 US visa prior to your journey.
If you are entering at a land border, this may not be immediately evident to the CBP officer and you may be granted entry without any issues, but if traveling by air it should be a flag from your APIS data and could potentially cause issues upto and including denied entry, expedited removal, permanent ineligibility for the VWP and a 5-year entry ban from the USA.
Some of the information in this post is incorrect. An individual entering the country via a land border under the Visa Waiver Program is not required to have a return airline ticket nor does the program require a residence permit in that "contiguous territory".
A Visa Waiver Refusal is not an Expedited Removal. Legally, they are very different dispositions. While a Visa Waiver Refusal will result in permanent ineligibly for the Visa Waver Program it will NOT have a five year entry ban. You can return to your country and apply for a visa, have it granted and be back in the US in a month. I have personally seen this happen many times.
FB