Proctor's output after he moved to New York City was prolific; among his creations in this period was the sculpture of the horse underneath William Tecumseh Sherman in Grand Army Plaza, bordering Central Park. (Most of the 1903 equestrian statue was by Augustus Saint-Gaudens; the architect of the installation was Charles Follen McKim.) In September 1909, Proctor was commissioned to design four large bronze tigers for the 16th Street Bridge in Washington, D.C. He made minor adjustments in the models, and then cast two more tigers to flank the steps of Nassau Hall at Princeton University. He also designed and cast some animal heads for the Bronx Zoo.