The library has two different addresses: 93 Caswell Avenue, Derby Line, Vermont, and 1 rue Church (Church Street), Stanstead, Quebec.
The library collection and the opera stage are located in Stanstead, but the main entrance and most opera seats are located in Derby Line. Because of this, the Haskell is sometimes called "the only library in the U.S.A. with no books" and "the only opera house in the U.S.A. with no stage". There is no entrance from Canada; however, there is an emergency exit on the Canadian side of the building. All patrons and visitors must use the U.S. entrance to access the building. Patrons from Canada are permitted to enter the U.S. door without needing to report to customs, providing they return to Canada immediately upon leaving the building.
A thick black line runs beneath the seats of the opera house and diagonally across the center of the library's reading room to mark the Canada–United States border. The stage and half of the seats are in Canada, the remainder of the opera hall is in the US. The building has different postal codes (93 Caswell Avenue, 05830 and 1, rue Church (Church Street), J0B 3E2) and different telephone area codes (+1-802-873-3022 and +1-819-876-2471) in its two respective countries.
The library has a collection of more than 20,000 books in French and English, and is open to the public 38 hours a week.
The building is recognized as a historic site in both countries. In the United States, it has been registered in the National Register of Historic Places since 1976. In Canada, it was designated a National Historic Site of Canada in 1985 and has been a provincial heritage site since 1977.
According to wikipedia