Why doesn the eruv include Fort Tryon Park?
The area of Ft Tryon Park is very large, and there are many physical a complexities involved in including it. Perhaps some day it will be expanded to include the park. The eruv does include two other nice parks: Bennett Park on Fort Washington between 183rd and 185th (which includes the highest point in Manhattan), and the Jacob Javitz playground, just south of the main entrance to Fort Tryon Park.
