The movie 12 years a slave.

• How could Northup be a free man in New York?

In New York and its neighboring areas slavery was outlawed and Northup was born a free man.

Explanation:

Solomon Northup was born a free man in New York because it was legally permissible for slaves to buy their freedom from their owners and slavery was even outlawed in some of the places of the country which did include New York at the time.

It was from there that he was lured into the south and then imprisoned promptly by the people there who ran a slave market racket there. he just had to find a way to reach north again to find his identity and then become free again