From the 1880's to 1943 the island was used to quarantine people with contagious diseases, like typhoid. There was one patient named Mary who had asymptomatic typhoid, and spread it to so many people which caused them to pass away, she was left at north brother until she passed away. In 1904 a steamship exploded 321, people survived, and 1,021 to wash up on the shore on North Brother. In 1950's they tried to run a drug rehab for teens but then was left abandoned in 1963.
It's an island so its ridiculously hard to get onto unless you have a boat or kayak.