Here's the info from the US Department of State
Applying for a Visitor Visa
Applicants for visitor visas should generally apply the U.S. Embassy or Consulate with jurisdiction over their place of permanent residence. Although visa applicants may apply at any U.S. consular office abroad, it may be more difficult to qualify for the visa outside the country of permanent residence.
Visa applications are now subject to a greater degree of review than in the past so it is important to apply for your visa well in advance of your travel departure date.
As part of the visa application process, an interview at the embassy consular section is required for visa applicants from age 14 through 79, with few exceptions. Persons age 13 and younger, and age 80 and older, generally do not require an interview, unless requested by embassy or consulate. Making your appointment for an interview is the first step in the visa application process. The waiting time for an interview appointment for applicants can vary, so early visa application is strongly encouraged. Visa wait times for interview appointments and visa processing time information for each U.S. Embassy or Consulate worldwide is available on our website at
Visa Wait Times , and on most embassy websites. Learn how to schedule an appointment for an interview, pay the application processing fee, review embassy specific instructions, and much more by visiting the
Embassy or Consulate website where you will apply.
Taken from
Visitor Visas Business and Pleasure