✔ 最佳答案
If you are British then you can get a visitor visa at the border for a maximum 90 days under the visa waiver program. The length of time is at the discretion of the border guard but cannot be longer than 90 days. This assumes you do not have a criminal record and that your passport is a biometric passport if issued on or after 26 October 2006 (machine readable if issued before 26 October 2006). If these assumption are incorrect, you need to visit the US embassy to apply for the visa.