“There was a longtime political agenda and focus on Manhattan-based landmarks,” said Kirsten Reoch, historian and archivist at the Park Avenue Armory. There are fewer preservation activists, and sometimes even a resistance to landmarking, outside Manhattan. Civic groups in wealthy Manhattan neighborhoods have traditionally driven preservation efforts. Manhattan, perhaps unsurprisingly, dominates the list with 20,679. The Landmarks Preservation Commission has designated more than 35,000 sites, when historic districts are included, since the Landmark Preservation Law was passed in 1965. Brownstones, high-rises and the ruins of a smallpox hospital. The Holland Tunnel, the Dakota and an art deco Sears department store in Flatbush. The Coney Island Wonder Wheel, Rockefeller Center and a magnolia tree in Bed-Stuy.