USCIS Service Center Operations is allowing petitioners and residents of Canada to file I-130 petitions for a spouse, parents and children with the US Embassy and consulates (other than Quebec). Instructions for the I-130 on the USCIS website provide the following:
"Petitioners residing in Canada can also file with the Vermont Service Center. United States citizens residing in Canada who are filing for their spouse, child, or parent, may now file at the nearest Embassy or Consulate, with the exception of Quebec City."