Exterior iron fire escapes spread as an inexpensive way to add a separate escape route to older, densely occupied housing. Their weaknesses included corrosion, structural damage, difficulty reaching them through windows, and stored objects blocking the route. New York later emphasized protected indoor stairs, fire compartments, and sprinklers, and its 1968 standards restricted exterior fire escapes on new buildings. Existing buildings did not all lose their fire escapes. City archival materials also show how fire safety rules in 1860, 1867, and 1879 changed escape facilities in existing housing.