本文发表在 rolia.net 枫下论坛I checked the web page of US state dept. and found the following words:

It states there is exception for landed immigrant. I am confused if it means we don't need visa at all to visit USA?

Who Needs an Appointment?
The appointment policy discussed below applies to the U.S. Embassy in Ottawa. The U.S. Consulates General located in Halifax, Quebec City, Montreal, Toronto, Calgary and Vancouver may have different appointment policies. Visa applicants residing outside of the U.S. Embassy's consular district should apply for visas at the appropriate Consulate General.
Third country nationals (i.e., non-Canadian citizens) who are visiting, living, working or studying in the United States and plan to apply for a new nonimmigrant visa at a Canadian or Mexican border post must have an appointment in advance. Third country nationals visiting Canada must also schedule an appointment to apply for a visa. The only exceptions are as follows:

1. landed immigrants to Canada who are presently residing in Canada
2. persons who have authorization to study or work in Canada and who are presently doing so or who are the dependent spouse or child of someone who has authorization to study or work in Canada and is presently doing so.

An appointment does not guarantee visa issuance. With limited exceptions, all nonimmigrant visa applications require a non-refundable US$45 application fee. Applicants should bring extra cash. Visas are generally ready for pickup at 3:00pm on the same day as the interview. Certain applications may require more lengthy processing.

In general, visitors who wish to travel to the United States should apply at the U.S. Embassy in their home country before departure, where they are better able to demonstrate their ties to a foreign residence as required under U.S. immigration law.

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