From Canada CSC, 06/13/2013
Important information for U.S. residents: Due to increasingly heavy demand by Canada-based visa applicants, U.S. visa processing posts in Canada are unfortunately extremely limited in the ability to accept visa applications from U.S. residents during the peak demand period of June through August. Appointments for visa renewals for U.S. residents who are currently studying or working in the U.S. will be more readily available during non-peak periods in October and November, and January through May.
For information on options for extending or renewing authorization to continue studies or employment while in the U.S., contact U.S. Citizenship and Immigration Services. Many travelers to Canada and Mexico are eligible for automatic revalidation at a Port of Entry without a new visa.
U.S.-based applicants who need a visa are encouraged to schedule an appointment in their home country. Information on worldwide appointment availability is found on the State Department’s website, www.Travel.State.gov.
From Fragomen.com, 06/10/2014
Third-Country National Visa Appointments Unavailable at U.S. Posts in Canada This Summer The Department of State has confirmed that third-country national (TCN) processing will not be available at any U.S. consular post in Canada from June to August 2014, except in emergency situations. TCN applicants with appointments already scheduled at a post in Canada during these months will not be affected.
The suspension will primarily affect foreign nationals who seek to renew a visa in Canada rather than travel to their home country. Appointments are expected to be available to foreign permanent residents of Canada, however.
From www.OgletreeDeakins.com, 06/04/2014
U.S. visa processing posts in Canada are urging third-country national (TCN) applicants to seek appointments at other U.S. Embassies and Consulates, such as those located in the applicants’ home countries. A TCN is an individual who applies for a visa at a U.S. Embassy or Consulate in a country where the individual is not a citizen or national.
The U.S. Department of State has reported that, as a result of heavy demand by Canada-based visa applicants during June, July, and August, the seven Canada posts are extremely limited in their ability to accept TCN cases during these peak demand months. Canadian posts will offer increased appointment availability for TCNs during non-peak processing times, namely October and November, and January through May. In the event of emergency cases during the peak demand period, applicants may seek consideration for scheduling an interview at a Canada post by visiting canada.usembassy.gov.