Are tripods and selfie sticks allowed on observation decks?

No. Most major observation decks—Empire State, Top of the Rock, Skydeck Chicago, etc.—ban both. Tripods are a tripping hazard, and selfie sticks are treated like weapons. Security will make you check them or turn you away. For stable photos, brace your phone against the railing or bring a tiny tabletop tripod, but check ahead first.