The University of Toronto is a good school, but no organization is going to go to the trouble of sponsoring you for an entry level Social Worker position in New York City. The job market is already over saturated with American citizens with the same or better qualifications, and to qualify for a visa your employer has to prove that no American citizen can perform your job - obviously that won't be the case. Perhaps as you gain more specialized skills, 10 or 20 years down the line you might have a niche expertise that is needed in New York, and at that point you might be more competitive for a visa. I know Social Workers do qualify for the TN1. Good luck!